Activate Kiki-Jiki by tapping it, creating a token copy of Goatnapper with haste.
The Goatnapper token enters the battlefield, untapping Kiki-Jiki.
Repeat.

Infinite creature tokens with haste

Infinite creature ETB

Kiki-Jiki, Mirror Breaker

Goatnapper

Maskwood Nexus

Activate Mirror Entity by paying {1}, causing creatures you control to have base power and toughness 1/1 and gain all creature types until end of turn.
Activate Kiki-Jiki by tapping it, creating a token copy of Goatnapper with haste.
The Goatnapper token enters the battlefield, untapping Kiki-Jiki.
Repeat from step 2.

Mirror Entity

Arcane Adaptation

Cast Volatile Claws by paying {2}{R}, causing creatures you control to get +2/+0 and gain all creature types until end of turn.
Activate Kiki-Jiki by tapping it, creating a token copy of Goatnapper with haste.
The Goatnapper token enters the battlefield, untapping Kiki-Jiki.
Repeat from step 2.

Volatile Claws

Xenograft

Cast Shields of Velis Vel by paying {W}, causing creatures you control to get +0/+1 and gain all creature types until end of turn.
Activate Kiki-Jiki by tapping it, creating a token copy of Goatnapper with haste.
The Goatnapper token enters the battlefield, untapping Kiki-Jiki.
Repeat from step 2.

Combos with "Goatnapper"