Agatha's Soul Cauldron + Ascendant Spirit + Devoted Druid + Doubling Season

Agatha's Soul Cauldron

Ascendant Spirit

Devoted Druid

Doubling Season

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 clever engine comes together by using Agatha's Soul Cauldron to feed the activated mana and untap abilities of Devoted Druid directly into Ascendant Spirit, turning green mana production into an infinite supply of untapped activations. Because Doubling Season is on the battlefield, any counters placed during this loop are massively amplified, allowing Ascendant Spirit to rapidly fulfill its own progression and stack up massive piles of +1/+1 counters and triggered abilities. Once the spirit is fully powered up and its card-drawing trigger has been replicated dozens of times, you simply swing into combat and draw your entire deck in a single glorious strike.