The Legend of Yangchen / Avatar Yangchen The Legend of Yangchen is a perfect removal spell for Commander because it hits permanents controlled by multiple players

Let's see what the rough ratios are for Vampiric Bloodlust and how it compares: 37 lands and 6 ramp: Sol Ring, Boros Signet, Orzhov Signet, Rakdos Signet, Worn Powerstone, Black Market 43 mana: Mathas, Fiend Seeker, Skeletal Scrying, Damnable Pact, Read the Bones, Ambition's Cost, Syphon Mind, Skullclamp, Heirloom Blade, Well of Lost Dreams, Underworld Connections, Outpost Siege 11 sources of card advantage: Captivating Vampire, Dark Impostor, Anowon, the Ruin Sage, Patron of the Vein, Drana, Kalastria Bloodchief, Vein Drinker, Butcher of Malakir, Swords to Plowshares, Go for the Throat, Crackling Doom, Mortify, Consuming Vapors, New Blood, Return to Dust 14 single target removal: Fell the Mighty, Merciless Eviction 2 board wipes: Bloodline Necromancer 1 recursion: 0 tutors Bojuka Bog 1 graveyard hate: Blood Tribute and Kindred Charge 2 surprise "I Win" cards: Vampiric Bloodlust has a ton of ways to remove opposing creatures that could get in the way of your army

Sidisi rewards your self-mill effects by giving you a 2/2 Zombie creature token when one or more creatures are put into your graveyard from your library, letting you get more value out of your triggers
That said, this does mean you have an obvious (and relatively cheap) first step to take when going about upgrading the deck
The Jund -1/-1 commander that is definitely, without a doubt coming in 2025
If you're rocking Islands, you want a full four copies