Rule 906.3b: if using the Partner mechanic, you may have 2 Oathbreakers.

The Signature Spell is linked to the deck, not the Oathbreaker per se, so you can play Jeaska & Tevesh with any Signature Spell in the Rakdos color identity.

I suppose the same goes for Will Kenrith & Rowan Kenrith, but in Izzet

After Counterspell is cast twice as a signature spell, it costs you which is not that scary anymore. Also, you need your Oathbreaker in play, the cheapest blue planeswalker is at least 3 mana. Keep up t4 counterspell doesn't sound as scary as you're making it out to be '^^

Also, the oathbreaker format website states that your starting life is 20, not 40

The exact wording of the rule is:

906.14 If another rule or effect refers to your commander, it instead refers to your Oathbreaker.

The Signature Spell would have had to be explicitly named there to be included in your Skull Storm count and such. The planeswalker, and only the planeswalker that is your Oathbreaker, is what's referenced to in this format as a "Commander" on commander-specific cards like Arcane Signet.

Nettle Cells

Tribal Enchantment - Jellyfish Aura

Enchant Creature

Enchanted creature is a blue jellyfish in addition to its other colors and types.

Whenever enchanted creature deals damage to another creature, copy the next instant or sorcery you cast once for each Jellyfish you control.

Create a legendary artifact with Flash

The companion is in addition to the 100 and I think should be represented in the sideboard. Your commander and 99 other cards must all 100 oblige to the companion deckbuilding rules.

We also already have enchantments with modes: Outpost Siege

Fair to say, a siege is a kind of battle, so it's not impossible, but with the dual-faced suggestion, and the fact that it's an entire new card type, I hope a battle is more than just an MDFC enchantment.

The reserved list does gatekeep Legacy and Vintage as paper-playable formats if you'd want to join in as a new player. That's the argument I've heard the most. And I agree with that, I wouldn't want to spend several monthly salaries to be able to sign up a deck for a real tournament. The price of modern staples is already pretty restrictive, and ABUR duals are orders of magnitude worse than a fetch/shock manabase is.

Of course there's value in keeping the reserved list to have your cards stay valuable and collectable, but the purpose of the cards for me is playing the game with it, and the cards that are so restrictive to obtain are at the same time the best to play with. That stings if you're more of a player than a collector, and that's what keeps this argument alive.

Quietly building up value and not getting on your opponents' bad side is not something that mono green does well. Because mono green's value lies in boardstate, and board presence always scares the opponent.

Especially if your commander is indestructible with deathtouch, that screams out: "I'M GOING TO FIGHT WITH ALL YOUR CREATURES AND IT WILL COST ME NOTHING!" and the other players at the table will resent you for being unable to build a boardstate themselves.

Even if your plan is just doubling your mana with a "power matters"-theme, as my Rhonas deck had when I played it, and I literally had only one fight spell in the deck, my experience is that laying low is not green's strength. It's the most Timmy color. So be enormous, be dangerous, and own it. Someone looks at you funny? Send a Ghalta, Primal Hunger at their face, and Ram Through their commander for good measure!

If you want to play mono green, embrace the color's strength. Don't try to play it like blue/black, those are green's enemy colors for a reason.