Cast Sandsteppe Mastodon by paying {5}{G}{G}.
Sandsteppe Mastodon enters the battlefield, putting five +1/+1 counters on Sage of Hours.
Activate Sage of Hours by removing all +1/+1 counters from it, causing you to take at least one extra turn after this one.
Move to your next turn.
At the begging of your upkeep, Stampeding Wildebeests triggers, causing you to return Sandsteppe Mastodon from the battlefield to your hand.
Repeat.

Infinite turns

Lock

Sandsteppe Mastodon

Stampeding Wildebeests

Sage of Hours

Cast Sandsteppe Mastodon by paying {5}{G}{G}.
Sandsteppe Mastodon enters the battlefield, putting five +1/+1 counters on Sage of Hours.
Activate Sage of Hours by removing all +1/+1 counters from it, causing you to take at least one extra turn after this one.
Move to your next turn.
At the begging of your upkeep, Roaring Primadox triggers, causing you to return Sandsteppe Mastodon from the battlefield to your hand.
Repeat.

Roaring Primadox

Cast Sandsteppe Mastodon by paying {5}{G}{G}.
Sandsteppe Mastodon enters the battlefield, putting five +1/+1 counters on Sage of Hours.
Activate Sage of Hours by removing all +1/+1 counters from it, causing you to take at least one extra turn after this one.
Move to your next turn.
At the begging of your upkeep, Species Gorger triggers, causing you to return Sandsteppe Mastodon from the battlefield to your hand.
Repeat.

Species Gorger

Cast Sandsteppe Mastodon by paying {5}{G}{G}.
Sandsteppe Mastodon enters the battlefield, putting five +1/+1 counters on Sage of Hours.
Activate Sage of Hours by removing all +1/+1 counters from it, causing you to take at least one extra turn after this one.
Move to your next turn.
At the begging of your upkeep, Stampeding Serow triggers, causing you to return Sandsteppe Mastodon from the battlefield to your hand.
Repeat.

Combos with "Sandsteppe Mastodon"