You have at least six other cards in your graveyard.
Mana Needed
({4} magic symbol) ({B} magic symbol) ({G} magic symbol) each other turn available.
Steps
Cast
Polukranos Unchained from your graveyard for its escape cost by paying ({4} magic symbol) ({B} magic symbol) ({G} magic symbol) and exiling six other cards from your graveyard, causing it to enter the battlefield with twelve +1/+1 counters on it.
Activate
Altar of Dementia by sacrificing
Polukranos Unchained.
When
Polukranos Unchained dies,
Yuna triggers, putting twelve +1/+1 counters onto
Sage of Hours.
Resolve the
Altar of Dementia ability, causing you to mill cards equal to
Polukranos Unchained's power.
Activate
Sage of Hours by removing all +1/+1 counters from it, causing you to take at least two extra turns after this one.
Repeat every second extra turn until you run out of cards to pay the escape cost.
Results
Near-infinite turns.
Metadata
This combo produces a lock.
In 0 decks according to EDHREC.
Bracket Tag
This combo has been estimated to be Ruthless (Bracket 4+).