You control at least one modified creature with power one or greater.
Steps
Activate Ashnod's Altar by sacrificing any other modified creature you control with power one or greater, adding ({C} magic symbol) ({C} magic symbol) .
One with the Kami triggers, creating a number of 1/1 Spirit creature tokens equal to the sacrificed creature's power.
The Spirit tokens enter the battlefield, triggering Cathars' Crusade that many times, putting that many +1/+1 counters on each creature you control.