Torsten dies, triggering itself and Nim Deathmantle.
Resolve the Torsten trigger, creating seven 1/1 Soldier creature tokens.
Activate Ashnod's Altar by sacrificing a Soldier, adding ({C} magic symbol) ({C} magic symbol) .
Resolve the Nim Deathmantle trigger from step 2, causing you to pay ({4} magic symbol) to return Torsten from your graveyard to the battlefield, and attach Nim Deathmantle to it.
Torsten enters the battlefield, allowing you to search the top seven cards of your library and put any number of creature and/or land cards from them into your hand.
Repeat.
Results
Infinite colorless mana.
Infinite creature tokens.
Infinite death triggers.
Infinite ETB.
Infinite LTB.
Infinite sacrifice triggers.
Put any number of creature and/or land cards from your library into your hand.