Infinite colored manaInfinite copies of most creatures you control with hasteInfinite creature tokens with hasteInfinite death triggersInfinite creature ETBInfinite creature LTBInfinitely large creature until end of turnInfinite creature sacrifice triggersInfinite untap of creatures you controlInfinite mana creatures you control can produce
How it works
Activate Kiki-Jiki by tapping it, creating a token copy of Composite Golem with haste.
Activate the Composite Golem token by sacrificing it, adding .
Activate Kiki-Jiki by paying 3 and untapping it, giving it +2/+2 until end of turn.
Repeat.
Once you have infinite mana, you may forego sacrificing the Composite Golem tokens and/or target any other nonlegendary creatures you control.
This clever loop begins with Kiki-Jiki, Mirror Breaker creating a hasty token copy of Composite Golem. Because the token is a creature, you can equip it with Umbral Mantle for free. By sacrificing the Composite Golem token for a colorful injection of five mana, you can then pump three of that mana right back into Umbral Mantle to untap the token, triggering its untap ability and growing it with +2/+2. The beauty of the system is that each cycle generates a net surplus of mana while keeping the token ready to repeat the loop, eventually leaving you with infinite colored mana and an army of hasty copies.