Activate Tooth and Claw by sacrificing two other creatures.
When the creatures die, One with the Kami triggers for each modified creature that died this way, creating a number of 1/1 Spirit creature tokens that each enter with a +1/+1 counter on them due to Thunderous Velocipede.
Resolve the Tooth and Claw ability, creating a 3/1 Carnivore creature token that enters with a +1/+1 counter on it due to Thunderous Velocipede.
Repeat.
This crafty loop transforms a simple pair of sacrifices into an overflowing menagerie through clever use of modified creatures. By utilizing Tooth and Claw to sacrifice two creatures, you trigger One with the Kami to flood the board with Spirit tokens based on the sacrificed creatures' power, which are instantly bulked up by Thunderous Velocipede's static ability granting +1/+1 counters to entering creatures. Those very counters ensure the newly birthed tokens and the resulting Carnivore token from Tooth and Claw count as "modified," keeping them primed to be fed right back into the engine for infinite deaths, tokens, and entry triggers.