Jin-Gitaxias // The Great Synthesis | Time Stretch

Cards

Time Stretch in hand.
Jin-Gitaxias (as
The Great Synthesis) and
Donnie & April on the battlefield (
Jin-Gitaxias with two lore counters on it).

At the beginning of your precombat main phase,
The Great Synthesis triggers, putting a lore counter on it. Its third chapter ability then triggers, causing you to cast
Time Stretch and
Donnie & April without paying their mana costs, and then exiling
The Great Synthesis and returning it to the battlefield as
Jin-Gitaxias.
Resolve
Time Stretch, causing you to take two extra turns after this one.
Resolve the
Donnie & April spell. When it enters, it triggers, returning
Time Stretch from your graveyard to your hand.
Activate
Jin-Gitaxias by paying ({3} magic symbol) ({U} magic symbol) , exiling it and returning it to the battlefield as
The Great Synthesis.
When
The Great Synthesis enters with a lore counter on it, its first ability triggers, causing you to draw cards equal to the number of cards in your hand and not have a maximum hand size for the rest of the game.
Move to your first extra turn. At the beginning of your precombat main phase,
The Great Synthesis triggers, putting a lore counter on it. Its second chapter ability then triggers, returning all non-Phyrexian creatures (including
Donnie & April) from the battlefield to their owner's hand.
Repeat from step 1 during your second extra turn.

The combo is listed as near-infinite turns because you'll draw cards at a much faster rate than normal, which will result in you getting less turns.

This combo has been estimated to be Ruthless (Bracket 4+).