Lost Jitte + Karn's Bastion + Cryptic Trilobite + Shang-Chi, Martial Mentor

Lost Jitte

Karn's Bastion

Cryptic Trilobite

Shang-Chi, Martial 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 ingenious loop turns Karn's Bastion into an infinite proliferation engine by leveraging the explosive growth provided by Shang-Chi, Martial Mentor. When Karn's Bastion proliferates, Shang-Chi doubles the counters added to Cryptic Trilobite and Lost Jitte, allowing Cryptic Trilobite's activated ability to generate more than enough restricted mana to pay for the Bastion's activation and the Lost Jitte ability used to untap it. In the end, Lost Jitte helps fund the mana loop while your entire board compounds infinitely under the Bastion's watchful eye.