Activate Thranduil using Immaculate Magistrate's ability by tapping it, putting a +1/+1 counter on Thranduil for each Elf you control.
Activate Thranduil using Devoted Druid's second ability by putting a -1/-1 counter on it, untapping it.
Repeat.

Infinite +1/+1 counters on creatures you control

Infinite green mana

Thranduil, the Elvenking

Devoted Druid

Immaculate Magistrate

Activate Immaculate Magistrate by tapping it, putting a +1/+1 counter on it for each Elf you control.
Activate Immaculate Magistrate using Devoted Druid's second ability by putting a -1/-1 counter on it, untapping it.
Repeat.
Once you have infinite +1/+1 counters on Immaculate Magistrate, you may instead target any other creature, or use Devoted Druid's first ability.
If you give other creatures +1/+1 counters, you may also untap them infinitely using Devoted Druid's second ability.

Infinite colored mana

Infinite mana creatures you control can produce

Infinite untap of creatures you control

Agatha's Soul Cauldron

Activate Immaculate Magistrate by tapping it, putting at least five +1/+1 counters on Sage of Hours.
Activate Sage of Hours' ability by removing all +1/+1 counters from it, causing you to take at least one extra turn after this one.
Repeat each turn.

Infinite turns

Lock

Sage of Hours

Activate Immaculate Magistrate by tapping it, putting a +1/+1 counter on it for each Elf you control.
Activate Immaculate Magistrate using Cinderhaze Wretch's second ability by putting a -1/-1 counter on it, untapping it.
Repeat.
Once you have infinite +1/+1 counters on Immaculate Magistrate, you may instead target any other creature, and you may also untap them infinitely using Cinderhaze Wretch's second ability.

Cinderhaze Wretch

Activate Immaculate Magistrate by tapping it, putting a +1/+1 counter on it for each Elf you control.
Activate Immaculate Magistrate using Barrenton Medic's second ability by putting a -1/-1 counter on it, untapping it.
Repeat.
Once you have infinite +1/+1 counters on Immaculate Magistrate, you may instead target any other creature, and you may also untap them infinitely using Barrenton Medic's second ability.
You may also repeat this loop whenever damage would be dealt to you or a permanent you control, and then use Barrenton Medic's first ability to prevent the damage.

Prevent all damage that would be dealt to permanents you control

Prevent all damage that would be dealt to you

Barrenton Medic

Activate Berta using Immaculate Magistrate's ability by tapping them, putting a +1/+1 counter on Berta for each Elf you control.
Berta's second ability triggers, adding one mana of any color.
Activate Berta using Farmstead Gleaner's ability by paying {2} and untapping them, putting a +1/+1 counter on Berta.
Berta's second ability triggers, adding one mana of any color.
Repeat.

Combos with "Immaculate Magistrate"