Activate Lulu by paying {3}{U}, causing you to proliferate and put a charge counter on Magistrate's Scepter.
Repeat step 1 two additional times.
Activate Magistrate's Scepter's second ability by tapping it and removing three charge counters from it, causing you to take an extra turn after this one.
Repeat each turn.

Infinite turns

Lulu, Stern Guardian

Magistrate's Scepter

Activate Lulu by paying {3}{U}, causing you to proliferate and put a +1/+1 counter on Crystalline Crawler, Workhorse and Cryptic Trilobite.
Activate Crystalline Crawler and Workhorse by removing a +1/+1 counter from them, adding {C}{U}.
Activate Cryptic Trilobite by removing a +1/+1 counter from it, adding {C}{C} that can only be spent to activate abilities.
Repeat.

Infinite proliferate

Crystalline Crawler

Workhorse

Cryptic Trilobite

Activate Avatar Kuruk by paying {20} minus {1} for each creature and/or artifact you can tap while activating it, causing you to take an extra turn after this one.
At the beginning of your end step, Conjurer's Closet triggers, blinking Avatar Kuruk and causing it to return to the battlefield as The Legend of Kuruk with a lore counter on it.
The Legend of Kuruk's first chapter ability triggers, causing you to scry 2 and draw a card.
Move to your next turn. At the beginning of your precombat main phase. The Legend of Kuruk triggers, putting a lore counter on it. Its second chapter ability then triggers, causing you to scry 2 and draw a card.
Activate Lulu by paying {3}{U}, causing you to proliferate and put a lore counter on The Legend of Kuruk.
The Legend of Kuruk's third chapter ability triggers, causing you to exile it and return it to the battlefield as Avatar Kuruk.
Repeat.

Combos with "Lulu, Stern Guardian"