Construct

This creature gets +1/+1 for each artifact you control.

Copy

(This token can be used to represent a token that's a copy of a permanent.)

{T}, Sacrifice this artifact: Add one mana of any color.

This creature gets +1/+1 for each other Rat you control.

Changeling (This token is every creature type.)

Enchant creature
Enchanted creature gets +1/+1.
When this Aura is put into a graveyard from the battlefield, each opponent loses 1 life.

Enchant creature
Enchanted creature has base power and toughness 1/1.

{2}, {T}, Sacrifice this artifact: You gain 3 life.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

{2}, Sacrifice this artifact: Draw a card.

(This creature is affected by summoning sickness, and it has "{T}: Add {G}.")

When this creature dies, you gain 1 life.