Activate Phyrexian Altar by sacrificing the creature with Nim Deathmantle attached, adding 1.
The creature dies, triggering Nim Deathmantle and One with the Kami.
Resolve the One with the Kami trigger, creating at least four 1/1 Spirit creature tokens.
Activate Phyrexian Altar three times by sacrificing three Spirit tokens, adding 3.
Resolve the Nim Deathmantle trigger from step 2, causing you to pay 4 to return the creature from your graveyard to the battlefield, and attach Nim Deathmantle to it.