Ob Nixilis, Captive Kingpin + Agatha's Soul Cauldron + Walking Ballista

Ob Nixilis, Captive Kingpin

Agatha's Soul Cauldron

Walking Ballista

How it works

1. Activate Ob Nixilis using Walking Ballista's second ability by removing a +1/+1 counter from it, dealing 1 damage to an opponent.
2. Ob Nixilis triggers, putting a +1/+1 counter on itself and exiling the top card of your library.
3. Repeat.

This loop transforms Walking Ballista into an engine of relentless attrition, fueled entirely by the activated ability it grants through Agatha's Soul Cauldron. Once Walking Ballista's activated ability pings an opponent for exactly 1 damage, Ob Nixilis, Captive Kingpin notices the life loss and triggers, placing a +1/+1 counter on itself while exiling the top card of your library. Because Agatha's Soul Cauldron grants creatures with +1/+1 counters all activated abilities of exiled creature cards, Ob Nixilis can immediately use Walking Ballista's counter-removal ability to repeat the process. This continuous cycle allows you to machine-gun down the table and exile your entire library in the process.