Yenna, Redtooth Regent + Ajani's Chosen + Ashnod's Altar

Yenna, Redtooth Regent

Ajani's Chosen

Ashnod's Altar

How it works

1. Activate Yenna by paying 2 and tapping it, creating a token copy of any Aura you control attached to any creature you control, then causing you to untap Yenna and scry 2.
2. Ajani's Chosen triggers, creating a 2/2 Cat creature token, then attaching the Aura token to the Cat.
3. Activate Ashnod's Altar by sacrificing the Cat, adding CC.
4. Repeat.

This elegant loop turns Yenna, Redtooth Regent into an endless enchantment-copying engine by leaning on the triggered ability of Ajani's Chosen whenever an Aura enters the battlefield. As the Chosen rewards each copy with a fresh 2/2 Cat creature token, Ashnod's Altar steps in to harvest that Cat for the exact amount of mana needed to pay for Yenna's activation cost. Because Yenna untaps herself whenever her copied creation is an Aura, you can simply feed the resulting sacrifices back into the loop to endlessly churn through your deck with infinite scrys and creature triggers.