Lost Jitte + Karn's Bastion + Cryptic Trilobite + Corpsejack Menace

Lost Jitte

Karn's Bastion

Cryptic Trilobite

Corpsejack Menace

How it works

1. Activate Karn's Bastion by paying 4, putting a charge counter on Lost Jitte and two +1/+1 counters on Cryptic Trilobite.
2. Activate Cryptic Trilobite's first ability twice by removing two +1/+1 counters from it, adding CCCC that can only be spent to activate abilities.
3. Activate Lost Jitte by removing a charge counter from it, untapping Karn's Bastion.
4. Repeat.

This loop turns Karn's Bastion into an endless engine of escalation by leaning on Corpsejack Menace to double every counter it distributes. As Karn's Bastion proliferates, it adds a charge counter to Lost Jitte and piles extra +1/+1 counters onto Cryptic Trilobite. Those accumulated counters on Cryptic Trilobite can then be removed for ability-restricted mana to fuel Karn's Bastion's activation cost, while Lost Jitte's charge counters cash in to untap Karn's Bastion and keep the cycle spinning.