Sliver Queen + Quickbeam, Upstart Ent + Devoted Druid + Maskwood Nexus

Sliver Queen

Quickbeam, Upstart Ent

Devoted Druid

Maskwood Nexus

How it works

1. Activate Devoted Druid's first ability by tapping it, adding .
2. Activate Devoted Druid's second ability by putting a -1/-1 counter on it, untapping it.
3. Activate Devoted Druid's first ability by tapping it, adding .
4. Activate Sliver Queen by paying 1, creating a 1/1 Sliver creature token.
5. When the Sliver enters the battlefield as a Treefolk due to Maskwood Nexus, Quickbeam triggers, giving Devoted Druid and up to one other creature +2/+2 until end of turn.
6. Activate Devoted Druid's second ability by putting a -1/-1 counter on it, untapping it.
7. Repeat.

This clever engine turns Devoted Druid into a self-contained mana source by cycling its untap ability, though traditionally those -1/-1 counters would eventually spell doom for the Druid. Enter Maskwood Nexus, whose passive typing transforms every token you create into a Treefolk alongside its other types. This ensures that every time Sliver Queen's activated ability pumps out a fresh body, Quickbeam, Upstart Ent's triggered ability flies off to buff your creatures and grant trample, all while the newly generated green mana sustains the loop.