Requires

Enduring Scalelord must be on the battlefield. Undercover Operative must be in hand. Cathars' Crusade must be on the battlefield. Mana needed:

Steps

1. Cast Undercover Operative by paying , choosing to have it enter the battlefield as a copy of Enduring Scalelord.
2. Undercover Operative enters the battlefield, triggering Cathars' Crusade, putting a +1/+1 counter on each creature you control.
3. Enduring Scalelord and Undercover Operative triggers.
4. Resolve the Undercover Operative trigger, putting a +1/+1 counter on itself.
5. Enduring Scalelord triggers, putting a +1/+1 counter on itself.
6. Repeat from step 4.

Results