Gaining a level won't remove abilities that a Class had at a previous level
You have to sacrifice a creature every turn to keep it, which, in a token deck, is a very small price to pay
In this deck it can remove finality counters from the artifacts you resurrect, letting you sacrifice and replay them again and again
They are nearly impossible to contain and highly intelligent, featuring physiological and neural capacities similar to humans
Being fairly cheap, cheating Commander Tax for casts 3+, and having a bit of evasion makes this a competent package
Rimefire Torque joins Adaptive Training Post with that same line of text, though this time its a tap ability so its harder to keep going off