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)
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
Later in the game you can play the key characters Belle Mechanic Extraordinaire and Beast Frustrated Designer earlier than their ink cost
Consul's Shieldguard: [Category 2] ETB yield is 2 Energy for 4 mana, then you can spend 1 Energy on an attack trigger to make another creature Indestructible
If you built Isshin when Kamigawa: Neon Dynasty came out, youre going to love this card
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