Nim Deathmantle triggers, causing you to pay ({4} magic symbol) to return
Ogre Chitterlord from your graveyard to the battlefield, and attach
Nim Deathmantle to it
When
Ogre Chitterlord enters the battlefield, it triggers, creating two 1/1 Rat creature tokens and giving Rats you control +2/+0 until end of turn if you control five or more Rats
Activate
Ashnod's Altar by sacrificing the Rat, adding ({C} magic symbol) ({C} magic symbol)
Repeat
Results
Infinite creature tokens
Infinite colorless mana
Infinitely powerful Rats you control until end of turn