Experiment Kraj + Devoted Druid + Ozolith, the Shattered Spire

Experiment Kraj

Devoted Druid

Ozolith, the Shattered Spire

How it works

1. Activate Experiment Kraj by tapping it, putting two +1/+1 counters onto Devoted Druid.
2. Activate Experiment Kraj using Devoted Druid's last ability by putting a -1/-1 counter on itself, untapping it.
3. Activate Experiment Kraj's own ability, putting two +1/+1 counters on itself.
4. Remove the -1/-1 counter and one of the +1/+1 counters from Experiment Kraj as a state-based action.
5. Repeat steps 2 through 4 any number of times, resulting in any number of +1/+1 counters on Experiment Kraj.
6. Activate Experiment Kraj using Devoted Druid's last ability by putting a -1/-1 counter on itself, untapping it.
7. Activate Experiment Kraj using Devoted Druid's first ability by tapping it, add .
8. Repeat steps 6 and 7 any number of times.
9. You may also activate Experiment Kraj's own ability any number of times instead of step 7, putting any number of +1/+1 counters onto creatures.

This ingenious loop centers around Experiment Kraj borrowing the activated abilities of Devoted Druid, whose self-untapping drawback is neatly circumvented by the way +1/+1 and -1/-1 counters cancel each other out as state-based actions. Because Ozolith, the Shattered Spire is present to amplify counter placement, Experiment Kraj not only generates infinite green mana through the druid's mana-producing ability, but also rapidly accumulates as many +1/+1 counters as you desire.