Tough Cookie

When this creature enters, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
{2}{G}: Until end of turn, target noncreature artifact you control becomes a 4/4 artifact creature.
{2}, {T}, Sacrifice this creature: You gain 3 life.

Agatha of the Vile Cauldron

Activated abilities of creatures you control cost {X} less to activate, where X is Agatha's power. This effect can't reduce the mana in that cost to less than one mana.
{4}{R}{G}: Other creatures you control get +1/+1 and gain trample and haste until end of turn.

Command Tower

{T}: Add one mana of any color in your commander's color identity.