Sita Varma, Masked Racer
Legendary Creature — Human Rogue
Exhaust — 
: Put X +1/+1 counters on Sita Varma. Then you may have the base power and toughness of each other creature you control become equal to Sita Varma's power until end of turn. (Activate each exhaust ability only once.)
Kai Carpenter
Aetherdrift (DFT)
• #223Rulings
If an exhaust ability of a permanent is activated, and then that permanent leaves the battlefield and returns to the battlefield, it becomes a new object so its exhaust ability can be activated again.
(wotc • 2025-02-07)
If an ability triggers whenever you activate an exhaust ability, that ability resolves before the exhaust ability resolves.
(wotc • 2025-02-07)
Exhaust abilities can be activated any time you could normally activate an ability.
(wotc • 2025-02-07)
Rulings
If an exhaust ability of a permanent is activated, and then that permanent leaves the battlefield and returns to the battlefield, it becomes a new object so its exhaust ability can be activated again.
(wotc • 2025-02-07)
If an ability triggers whenever you activate an exhaust ability, that ability resolves before the exhaust ability resolves.
(wotc • 2025-02-07)
Exhaust abilities can be activated any time you could normally activate an ability.
(wotc • 2025-02-07)