Agatha's Soul Cauldron + Ascendant Spirit + Devoted Druid + Branching Evolution

Agatha's Soul Cauldron

Ascendant Spirit

Devoted Druid

Branching Evolution

How it works

1. Activate Ascendant Spirit using Devoted Druid's first ability by tapping it, adding .
2. Activate Ascendant Spirit using Devoted Druid's second ability by putting a -1/-1 counter on it, untapping it.
3. Repeat three additional times.
4. Activate Ascendant Spirit's third ability by paying SSSS, putting four +1/+1 counters on it and causing it to gain the listed ability.
5. Repeat until the number of instances of Ascendant Spirit's gained ability is equal to your deck size.
6. Move to your combat phase, and deal combat damage to an opponent using Ascendant Spirit.
7. Ascendant Spirit triggers once for each instance of the gained ability it has, causing you to draw that many cards.

This ingenious loop turns Devoted Druid's self-untapping mana engine into a source of infinite snow mana by using Agatha's Soul Cauldron to grant Ascendant Spirit all of the Druid's activated abilities from exile. Branching Evolution supercharges this interaction by doubling every counter placed by Ascendant Spirit's final level-up ability, allowing you to rapidly stack up massive numbers of +1/+1 counters and trigger instances. Once Ascendant Spirit is fully powered up and its card-drawing ability is duplicated through repeated activations, a single strike in combat will draw your entire deck.