Yenna, Redtooth Regent + Instill Energy + Phantatog

Yenna, Redtooth Regent

Instill Energy

Phantatog

How it works

1. Activate the mana-producing creature by tapping it, adding at least 2.
2. Activate Yenna by paying 2 and tapping it, creating a token copy of Instill Energy attached to the mana-producing creature, then untapping Yenna and causing you to scry 2.
3. Activate the Instill Energy token by paying 0, untapping the mana-producing creature.
4. Activate Phantatog's first ability by sacrificing the Instill Energy token, causing Phantatog to get +1/+1 until end of turn.
5. Repeat.

This loop turns Yenna, Redtooth Regent into an enchantment-copying engine by enchanting her with Instill Energy, whose free once-per-turn untap ability is bypassed entirely because Yenna's own resolution untaps her whenever she copies an Aura. While Yenna handles the cloning, Phantatog acts as the crucial sacrifice outlet, letting you feed away the freshly created Instill Energy tokens to continuously pump its stats. Because Yenna untaps herself in the process, you can repeat this cycle to fuel Phantatog infinitely while sifting endlessly through your deck with infinite scrys.