Gavi, Vicious Cycler v1.1.OTJ (EDH / Commander) [Revision 110]

'Gavi, Nest Warden' is fueled by +/- 40 cycling cards and other symbiotic card draw and token synergies.

Utility comes at a slight premium by casting cards with cycling ability such as Neutralize or Cast Out, but other cards offer hard-to-counter add-on triggered-by-cycling abilities, including discounted tokens via 'Decree of Justice', free land wipe with 'Decree of Annihilation' and free counter-spell via 'Decree of Silence'.

The engine, a positive feedback loop between Gavi and 'Rielle, the Everwise' or 'Ephara, God of the Polis'. 'The Locust God' and Ephara work the similarly. Additionally, 'Mindmoil' triggered by your instant spells draws out a fresh hand during opponent turns, generating tokens from Gavi, Locust God or via enchantments Drake Haven or Hoofprints of the Stag. 'Harmonic Prodigy' doubles Gavi's token generation. Additional card draw sources 'Welcoming Vampire', 'Bennie Bracks, Zoologist', 'Mirror-Sigil Sergeant', 'The Council of Four', 'Idol of Oblivion' or 'Dack Fayden' also contribute to the feedback loop.

'Moderation' is an interesting play as you'll be cycling, rather than casting, more often, thus minimizing it's penalty. Similarly, 'Fires of Invention' free spells keep your mana up for second and third cycles on any turn which isn't affected by Fires conditions. Either of these plus Mindmoil can trigger heavy card draw for Locust God, as can 'Reconnaissance Mission' and attacking with a locust swarm.

Planeswalkers: 'Dack Fayden' is early ramp fixing: take an opponents mana rock when he comes into play, or use his + ability to trigger Gavi. 'Elspeth Tirel' is a win-con with her -5 clearing the board for a token finale.

'Zirda, the Dawnwaker' reduces activated ability costs, from 'Sokenzan, Crucible of Defiance' and 'Hoofprints of the Stag' token generation to infinite colorless mana via 'Basalt Monolith' and reduced cycling costs after Gavi's first each turn.

Empowering the token swarm, 'Anointed Procession' doubles output. 'Akim, the Soaring Wind' adds tokens and grants all tokens double strike. 'Elesh Norn, Grand Cenobite' can clear the path for a token invasion. Akroma's Will as coup-de-grace.

Honorable mentions:

Approach of the Second Sun - a readily accessible secondary win-con from the side board with the high card draw.
Desolate Lighthouse - card draw from the land slot.
Strionic Resonator - double Gavi's trigger.
Brudiclad, Telchor Engineer - provides haste and allows a change of all tokens to your best type.
Divine Visitation - converts any token created into a vigilant 4/4 flyer.