Im going to repeat this again to make my position clear: Farewell cast on all modes is back-breaking and it often hurts the person that casts it at least as much as their opponents
A truly colorless creature needs to be unaligned with what the five colors of Magic can do, and it cant do something neutral and particularly powerful for a cheap cost since that would be easily exploitable
Glasspool Mimic follows in the footsteps of Jwari Shapeshifter in that it's cheaper than the run-of-the-mill four-mana clone at three mana and has a drawback (it can only copy creatures already under your control)
I love the base BW human aggro decks I've got to play in cube though and I really encourage people seeing what they can get from cubing multiples of human enablers etc
The supply here will be more than enough to satiate the Modern demand for the card, which means the price will fall accordingly
Having three mana dorks (including Deathrite) in the list is a little extreme given how cheap the deck is but two of them are doing other very useful things as well, some of the things you make are mana intense, it allows you to skimp a little more on lands and it gives you extra burst