Sun Titan attacking every turn + Second Chance + your life total is 5 or less = infinite turns
How it works:
- At the beginning of your upkeep, if you have 5 or less life, Second Chance's triggered ability will trigger, causing you to sacrifice it and take another turn after this one
- During this turn, attack with Sun Titan, using its triggered ability to return Secon Chance to the battlefield
- Repeat