Lullmage Mentor + Adrix and Nev, Twincasters + Mondrak, Glory Dominus + Elspeth, Storm Slayer

Lullmage Mentor

Adrix and Nev, Twincasters

Mondrak, Glory Dominus

Elspeth, Storm Slayer

How it works

1. Whenever an opponent casts a spell, activate Lullmage Mentor by tapping seven untapped Merfolk, countering that spell.
2. Lullmage Mentor triggers, creating a total of eight 1/1 Merfolk creature tokens.
3. Repeat.

This loop locks down the stack entirely by weaponizing Lullmage Mentor's activated ability to counter an opponent's spell, which immediately triggers its own counter-buff to spawn a fresh wave of fish. Thanks to the explosive token-doubling effects of Adrix and Nev, Twincasters, Mondrak, Glory Dominus, and Elspeth, Storm Slayer all stacking together, that single trigger yields an overwhelming surplus of eight Merfolk tokens at once. With your army instantly replenished, you have more than enough untapped bodies to pay Lullmage Mentor's cost again, locking out any subsequent spells your opponents attempt to cast.