Aethersnipe + Gwenna, Eyes of Gaea + Duskwatch Recruiter // Krallenhorde Howler

Aethersnipe

Gwenna, Eyes of Gaea

Duskwatch Recruiter // Krallenhorde Howler

How it works

1. Activate Gwenna by tapping it, adding that can only be spent to cast creature spells or activate abilities of creatures.
2. Cast Aethersnipe for its evoke cost by paying .
3. Gwenna triggers, putting a +1/+1 counter on it and untapping it.
4. When Aethersnipe enters the battlefield, its first ability and evoke ability trigger.
5. Resolve the first Aethersnipe trigger, returning it from the battlefield to your hand.
6. Resolve the second Aethersnipe trigger, failing to sacrifice it as it is no longer on the battlefield.
7. Repeat.

This elegant loop relies on Gwenna, Eyes of Gaea to provide the exact blue mana needed to cast Aethersnipe for its evoke cost, while its passive ability untaps Gwenna and grows her with a +1/+1 counter every time that creature spell is cast. Because Aethersnipe immediately bounces itself back to your hand with its enters-the-battlefield trigger before the sacrifice trigger can resolve, you can replay it over and over. While Duskwatch Recruiter's front face isn't strictly necessary for the core loop to close, its back face (Krallenhorde Howler) can even help discount your creatures if you decide to weave it into a larger turn.