Lost Jitte + Karn's Bastion + Cryptic Trilobite + Conclave Mentor

Lost Jitte

Karn's Bastion

Cryptic Trilobite

Conclave Mentor

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 engine transforms Karn's Bastion into an infinite proliferation machine by leaning heavily on how replacement effects and counter manipulation interact. With Conclave Mentor on the board, every time Karn's Bastion proliferates to add counters, the Cryptic Trilobite receives an extra +1/+1 counter—fueling its ability to generate the exact colorless mana needed to activate the Bastion again. Meanwhile, Lost Jitte passively tracks the charges on itself and provides the crucial untap effect for Karn's Bastion using that same mana, closing the loop into a self-sustaining cycle.