Cazur, Ruthless Stalker

Partner with Ukkima, Stalking Shadow (When this creature enters, target player may put Ukkima into their hand from their library, then shuffle.)
Whenever a creature you control deals combat damage to a player, put a +1/+1 counter on that creature.

Ukkima, Stalking Shadow

Partner with Cazur, Ruthless Stalker (When this creature enters, target player may put Cazur into their hand from their library, then shuffle.)
Ukkima, Stalking Shadow can't be blocked.
When Ukkima leaves the battlefield, it deals X damage to target player and you gain X life, where X is its power.

Gaea's Skyfolk

Jhessian Infiltrator

Dauthi Slayer

Shadow (This creature can block or be blocked by only creatures with shadow.)
Dauthi Slayer attacks each combat if able.

Island

Inkfathom Infiltrator

Inkfathom Infiltrator can't block and can't be blocked.