Glad that could help a bit, for sure the most frustrating thing I find in Magic is when you just draw terrible, but learning to accept the good with the bad is part of getting better I've found, that and eventually figuring out how to look for the pitfalls rather than just get annoyed. For me, it wasn't until I learned to take the good with the bad that I started looking at hypergeometric stuff differently, good deck building is about minimizing the number of bad hands while improving the odds of winning.

TBH I couldn't believe people even tried other Reanimation options, Griselbrand is mostly better Yawgmoth's Bargain, that's better than anything legal in Modern isn't it?

May you draw your bolts when you need em!

I got curious so I ran some numbers through the old hypergeometric calculator, I do this whenever I want to decide if I'm angry at my deck or not, I'm usually surprised to realize that what feels like a 'terrible hand' is actually reasonably likely to come up, this can be a clue to me to change my deck sometimes, because if I don't like drawing statistically normally. It can also be helpful to deter me from changing a deck, when some quick numbers reveal that a particularly bad hand won't come up very often.

Anyways, if you managed to get so far as to have only 40 cards left in your Library with all 4 bolts, and had life to draw 14 more cards you're whiffing over 16% of the attempts, that's not quite 1/5th of possibilities.

If you had only 30 cards in the library the odds improve obviously, but you'd still be whiffing over 6% of the time, and that's when you're drawing almost half your remaining cards.

If you started with only 20 cards in your library you'd whiff less than 1/3 of a percent of the time, if you whiffed when you were at 20 I'd say you should be salty if that's 'fun' for you.

I'm not sure how fast you usually end games, but I love Field of the Dead in my Voltron decks, it's ability to generate blockers is usually very relevant by the time it's active. It's best in a Green deck, where you often run land ramp effects over stuff like Arcane Signet, but technically if you fetch Jetmir's Garden it'll still enter tapped, and Signet doesn't, I just hate stuff like Vandalblast wiping me out, they price the effect so low. Anyways, if you wanted to run Field of the Dead, you would probably switch out 1 of each Basic for a Snow-Covered version (you'd only need 3, so it's not a big investment), these have a different name and can help turn on Field! Other things that might help Field work are Crop Rotation, since you run Ancient Tomb (and Sanctum!) I think this is a must anyways, Open the Way is a truly great ramp effect, Farseek is another spell that can find a typed dual or tri, the only thing it can't find is a Basic forest, which is usually fine when you've already got Green in my experience. Considering you're using some pretty strong lands I would consider Hour of Promise, it's a Primeval Titan trigger for less mana, but you just get the one. With lands this good getting two of them should give you a pretty big edge. Into the North can find a Snow land, which would help in a Field of the Dead deck. I suspect with a 5 mana Commander your deck will run smoother if you could find space for a few more lands, up to you obviously but I do suggest a few lands you could consider. At the same time I'd also toss in a few more ramp effects, Green has some good ones, ones that survive the board wipes people will be tutoring up vs a deck like this!

If you're on Serra Sanctum, I feel like mentioning a few cards I like to use with it, to eek out a bit more value. Ruin Ghost can flicker it and generate a bunch of mana, as can Nature's Chosen (which is even an Enchantment!), you might even look at Deserted Temple (probably the worst option all told). Kessig Wolf Run is a card I don't run with Sanctum (I don't have Red i that deck), but plays very well with large amounts of mana, and if you're stuck playing vs a guy that keeps wiping your board. I'm always impressed by it's ability to generate a threat from a weenie, I imagine it'll be more effective with your Commander. Normally I run Wolf Run as much for Trample as the buff, but you do have a lot of Trample sources in here.

Oh yeah, I just remembered a weird trick I like to use in a Boros deck (it was desperate for card draw and I didn't want to spend even more), I settled on using Crown of Flames and Flickering Ward as auras that I could recast over and over. You could also use Whip Silk if you wanted, but the only one of those that seems worth the include in a deck this competitive is Ward, which can make you very hard to block vs some boards, but I think you'd mostly have it to trigger your Enchantress cards.

Targeting is done up front (with Arena you make your choice then the opponent does, for each copy of the effect, as the card's text reads), triggers from different players resolve in reverse turn order (if it's your turn yours go on the stack first, then opponents in turn until the player who precedes you, who's effects resolve first). I'm fairly confident you don't have two triggers on the stack for Arena, just one that involves both players.

In short I think targets are picked for each copy as it goes onto the stack, with you targeting first, then the opponent choosing the second target. The effects then resolve normally, first in last out, so if you somehow created lots of Arena effects simultaneously your opponent can just make all the fights target the same chump and as soon as the chump dies the rest fizzle (but apparently it still taps stuff according to Scryfall).

I got up pretty early this morning, hope I'm not way off base!

Sorry I brought Storage Lands up if you've got such bad memories of them!

My 2 cents is that you probably can keep some of the better low to the ground ramp to help get to the more splashy options online, having only high MV ramp with a relatively low land count might not work ideally, having some faster rocks will lead to some games where you have an early Sol Ring into a Thran Dynamo!

I totally understand not wanting infect, it's just hard to not mention something with that level of synergy, I often struggle with 'deck flavor vs powerful cards' problem, nice to see you've got a great handle on it! I guess Inquisitor's Flail has a bit more of a flavor win, since the flail theoretically bops the creature for double as well, but with Protection it won't come up.

If you want to encourage people to attack there is always Angel's Trumpet, this also punishes people for not playing the game you want them to. Nemesis Mask would be avoiding using your Commander for damage and might have some flavor win to it (not only can all of your other attackers get in, Teysa gets to deal her damage to any blocker you want, Banding aside, so you can potentially kill off some utility creatures with each swing), it lets you make use of Vigilance without dealing Commander damage!

If you like paying life Kothophed, Soul Hoarder will let you pay a ton of life/live fast, the better the decks people play the more cards you'll end up drawing. I'm really trying to avoid the 'commander damage' thing, but what about Hatred? You pay life and remove a player who needs to be gone ASAP, then switch life? I could see that being too 'Voltron' for your tastes, but maybe it's on flavor enough to get a pass?

I've heard of people building this type of deck around Selenia, Dark Angel before, maybe she'd work in the 99 to pay life with something like Axis of Mortality's trigger on the stack? She's also an evasive and can protect herself, so she's not 1 dimensional, but a 3/3 isn't very big in Commander!

Hope this stuff isn't too voltron-y for you!

Just some 'bad' ideas to consider (I have some irregular views on ramp, to be polite), Subterranean Hangar is ramp that uses a land drop, very handy with a 7 mana Commander, either to get them out or recast them, Fountain of Cho is the White option. I threw cards like this in a deck on a lark, I was pretty impressed how they can play out in a deck that uses fairly splashy effects... this brings me to Grave Betrayal, this card is politely described as 'good with your Commander'. Another option to consider is bigger ramp, maybe Thran Dynamo, which takes you from 4 mana to enough to cast your Commander next turn, seems decent? Maybe Gilded Lotus, which takes you from 5 to 8, but also gives you coloured mana? Worn Powerstone is also interesting, it's not a great card but it's also not unplayable, wildly worse Sol Ring is also a good enough card, it just looks bad because Sol Ring exists. Another choice worth looking at that is relevant because of it's ceiling is Skyclave Relic, the kicker is a bunch, but that much mana next turn is advantageous. I get that your deck is trying to be fairly nimble, with lots of lower to the ground ramp, but I feel like with a 7 mana Commander that does this much you really want her out as quickly and consistently as possible.

If you like Indestructible sources, I think Gift of Doom is the best ever printed, Morph is incredibly hard to interact with once it's in play, and I'd like to think you'll have some sac fodder. It's also a combat trick fwiw, you've got Vigilance, and if they've got a big attacker this can deal with them and prevent certain types of removal, and it can blank stuff at the fastest speed possible.

Since your Commander has Protection from Creatures, I'd love to see if Inquisitor's Flail would work in here? By itself it turns your Commander into a 3 turn clock vs any opponent, and she blocks better since she'll deal double damage. It's less resources than Fireshrieker, but it completely stacks with it fwiw, if you get two doubles you're a 2 turn clock. Come to think of it I think I'd run Duelist's Heritage over Fireshrieker if you have access to White. Another 'out there' idea, but Grafted Exoskeleton plays well with your Commander, it turns her into a 2 turn clock by itself, and your Commander becomes a pretty nasty blocker too, and it obviously would play well with doublers. If you've got Protection from Creatures, you could try Pariah on your Commander to drag out games. It's worse if people play Red Burn effects in your area, but at least life loss effects don't interact with it, just damage. If you have Indestructible on something then Pariah looks even better.

I hope some of these ideas are useful, Big Teysa is a nifty Commander to see in action!

I have no idea if you want random input on this, so ignore this if you don't!

It might clog up your mana base, but you could sneak a few more creatures by throwing in a couple man-lands to replace other lands. With Nadu you'd put them directly into play, and even if they ETB tapped they can still become a creature and be targeted. There are a few that only use 1 mana to transform (such as Mishra's Factory and Inkmoth Nexus/Blinkmoth Nexus), but a few that turn on for 2 mana exist as well (Treetop Village, Faerie Conclave, Lair of the Hydra, and Mishra's Foundry), I feel like with all your 'free mana whenever a land ETBs' effects you'll easily be able to use them when you need them. The ETB tapped ones are worse (but usually offer colored mana), but as noted you'll usually see a given land when you're using Nadu (because you go through so many more cards with Nadu than you draw normally), so all that matters is they are creatures too, when I was testing this the issue was running out of creatures and not being able to continue, I often had gobs of mana I had no real use for (I will say the deck can easily hold up a hand full of interaction after using Nadu, even if you don't truly 'go off'). I took a quick look at your land list, and if I wanted to pull a couple lands I think Talon Gates of Madara has low synergy, I'd also consider Nesting Grounds, and since you have a few removal spells you might even switch out Homeward Path, depending on how theft-heavy your meta is.

Since you can generate a fair bit of mana in this deck when you're going off (and playing it for 4 or 5 mana in a slow game could also be a solid play) I think Awaken the Woods might do work in here.

It's pretty minor, but Whir of Invention costs one more (but has improvise fwiw), it doesn't require you to have an existing Artifact out, and it's an Instant so you can use it on an opponent's end step to get your Shuko out so you can go off on your turn. I think this is more than you can do with Reshape, ymmv.

It's a niche use, but if you switch out Amphibian Downpour (a card I legit love btw) for Curse of the Swine you'd have the option of targeting all of your disposable creatures and replacing them with brand spanking new piggies! These can be targeted anew, meaning if you draw into it at the right time it should win the game. It can also be used aggressively to excellent effect (and can do both at the same time), it sucks that it's a Sorcery though!

This is really splitting hairs a bit, but with your Commander I wonder if good old Sunder might be better at doing what Mana Vortex does? Sunder's an Instant (so you can play it on an opponent's endstep), and as long as you've already got Nadu and a free equip out you'll be fine on your turn, but it's also a much worse Blue Silence effect you can use during your combo to make it much harder to interact with you, and you just keep digging out new lands so it's all good? I love Mana Vortex and think it's doing a different enough thing that both could be fun. You could also try out Winter Orb and Static Orb if you're feeling, well, 'orbsy', both make it much harder to use lands, and you get to cheat a ton in untapped if all is going well.

Hope your testing is going well!

Oh, it looks like you have 99 cards, what a lovely problem to have!

I built a discard deck of my own awhile back, though mine is Dimir (I went with Sygg, River Cutthroat for the card draw) there might be a few cards that are worth a look!

It might get you killed since you're not running hard Stax like Static Orb in here, but Bloodchief Ascension is a really strong card in a discard deck. If you get this out early, it can easily take over a game.

Since you have Creeping Dread in here, maybe Stronghold Rats? Maybe Necrogoyf? Painful Quandary is a lot of mana for a reasonably strong effect, especially if you have any additional effects out with it. I threw in a bunch of racks that hit each opponent (stuff like Wheel of Torture, Rackling, and Shrieking Affliction), I found these helped speed things up.

I'm not sure if you are interested in stuff like Crawlspace, Ensnaring Bridge, or Koskun Falls? They are handy in a discard deck because people often want you dead as soon as they realize your going to make them discard all the fun stuff they're holding up, protection type Stax can be very helpful in my experience. I have a few more, mostly weirder ones, if you want to lean into the area, but it's not THAT deep unless you throw in hard Stax (like Static Orb and Meekstone).

I don't use them in my own discard list, but I also like Shizo, Death's Storehouse for the Fear. Maybe Access Tunnel and/or The Black Gate?