The way Jetmir works is that once you hit various creature count thresholds you unlock a new ability

"Lifetime" Pass Holder Admiral Beckett Brass Admiral Brass, Unsinkable Aerial Assault Agate Assault Agate-Blade Assassin Aggravated Assault Alchemist's Assistant All-Out Assault Alley Assailant Allied Assault Amass the Components Ambassador Blorpityblorpboop Ambassador Laquatus Ambassador Oak Ambitious Assault Ancient Brass Dragon Arcane Spyglass Armed Assailant Artificer Class Artificer's Assistant Ass Whuppin' Assassin Den Assassin Gauntlet Assassin Initiate Assassin's Blade Assassin's Ink Assassin's Strike Assassin's Trophy Assassinate Assault // Battery Assault // Battery Assault Formation Assault Griffin Assault Intercessor Assault Strobe Assault Suit Assault Zeppelid Assault on Osgiliath Assaultron Dominator Assemble from Parts Assemble the Entmoot Assemble the Legion Assemble the Players Assemble the Rank and Vile Assembled Alphas Assembled Ensemble Assembly Hall Assembly-Worker Assert Authority Assert Perfection Assimilate Essence Assimilation Aegis Assquatch Assure // Assemble Assure // Assemble Athreos, God of Passage Automated Assembly Line Autonomous Assembler Avengers Assemble

The power of Dark Sage allows it to have total control over your spells and trap cards, as your opponent cannot destroy them
In addition, there are 36 foil lands, 24 foil commons/uncommons, 16 full-art basic lands, 12 rare/mythic rares, and 1foil double-sided token
What makes this whole thing really absurd though, is that you when you cast an Equipment spell like that, it gains When this Equipment enters the battlefield, attach it to target creature you control. That means that all you have to do is cast an Equipment from the top of your deck, and suddenly youve bolstered your attack and defence substantially
Like many catch-up cards, however, Keeper of the Accords effectiveness directly scales with how many opponents are ahead of you, and can be an absolutely dead card if youre already winning