Also, Lifelink is a terrible include. Do not recommend.

Enchantress inclusions

Setessan Champion & Sythis, Harvest's Hand are some new and good enchantress options

Mana Fixing

Sanctum Weaver scales with all your auras

Jukai Naturalist & Herald of the Pantheon are a medallion for your enchantments

Delighted Halfling makes your commander and all legendaries uncounterable

Protection

Teferi's Protection & Flawless Manuever & Everybody Lives! are great general protection spells

Mithril Coat has flash and can protect your sigarda in a pinch and make her borderline unremovable.

Veil of Summer is OP nonsense

Myrel, Shield of Argive is a legendary Grand Abolisher with upside

Synergy Picks

Yenna, Redtooth Regent copies your auras and untaps can make you sigarda huge very quickly if you have the mana

Almost Perfect sets Sigarda's Base P/T to 9/10 and she can still be buffed

Well Rested for the buffs, life and draw all for 2 mana

Hope this helped

I would add more mana dorks: Ignoble Hierarch adds Jund colors and gives exalted as a bonus Deathrite Shaman acts as graveyard hate and can drain/gain at instant speed on on top of exiling any lands from anyone's graveyard for mana of any color also at instant speed. Delighted Halfling adds colorless or any color for legendary creatures and makes them uncounterable.

I would also add more aristocrat/sacrifice effects: Korvold, Fae-Cursed King crazy draw engine with sac synergy and a potential one-shot kill if he gets big enough Mahadi, Emporium Master generates treasures EOT based on how many creatures died, setting you up for big plays in the coming turns Pitiless Plunderer generates treasures whenever another creature you control dies immediately Chatterfang, Squirrel General basically a 3 mana Parallel Lives. Goes infinite with Pitiless Plunderer 1.Activate Chatterfang by paying b and sacrificing two other Squirrels. 2.The Squirrels die, triggering Pitiless Plunderer twice, creating two Treasure tokens and two 1/1 Squirrel tokens. 3.Activate a Treasure token by tapping and sacrificing it, adding b. 4.Repeat. 5.Resolve all Chatterfang abilities, causing any number of target creatures to get +2/-2 until end of turn any number of times. This gives you: Infinite colored mana. Infinite death triggers. Infinite ETB. Infinite LTB. Infinite sacrifice triggers. Infinite Treasure tokens. Reduce all opponents' creatures to 0 toughness.

Some pay off for sacrificing Mirkwood Bats, Blood Artist, Garna, Bloodfist of Keld & Poison-Tip Archer are good win condition for infinite sac outlet effects

Some better tutor effects: You can replace Diabolic Tutor for some other options below Diabolic Intent Tutor for 2 mana for any card with an additional sac requirement for sac effect synergies Demonic Tutor The OG best tutor Diabolic Revelation You wanna be cheeky? If you have big mana you can dump it all to grab multiple pieces to win the game

Some ramp effects: Cultivate & Kodama's Reach puts one to hand one to battlefield Nature's Lore & Three Visits puts any forest card onto the battlefield Entish Restoration is a new card that is better than harrow because you sacrifice a land on the resolution of the spell rather than paying the additional cost upfront, which makes it more safe from a feels-bad counterspells which puts you down a land. If you have a big enough creature you get 3 basics to the field all at instant speed as well. Nissa, Vastwood Seer  ^Flip is a pet card of mine which allows you to search for a basic and when you have 7 lands she flips and generate lands and card draw for pretty much free. Oracle of Mul Daya Allows you to play an additonal land every turn and allows to play them off the top of your library. If you dont see a card you like you can shuffle it away with a fetch land to try to get another off the top.

Better Lands: Urborg, Tomb of Yawgmoth & Yavimaya, Cradle of Growth are must includes allowing all your lands tap for B/G respectively in addition to your other colors. The pain lands Llanowar Wastes, Karplusan Forest & Sulfurous Springs are cheap dual lands that give you all your colors The reveal lands Game Trail, Foreboding Ruins & Necroblossom Snarl are also good cheaper options which give you dual colors The shocklands Blood Crypt, Overgrown Tomb & Stomping Ground are fetchable and come into play untapped for a measley 2 life are some of the best lands in the game Verdant Catacombs is the last fetch of your color not included. I would include it if you could because it allows all three of your fetches to fetch any of your shocks or battlelands. You can also include other Fetchlands as well such as Arid Mesa, Misty Rainforest etc to fetch because they can fetch for one of the jund colors of lands at least, however, they aren't as efficient Ziatora's Proving Ground is a must include because you can fetch it out and it taps for jund as well as cycle if it comes too late. If you don't have a turn one play you can fetch it out as your best land with no plays.

Hopefully this helps