Sanctum of Eternity
Land
: Add 
.
, : Return target commander you own from the battlefield to your hand. Activate only during your turn.
Come and rest here, beyond the constraints of space and time.
Daniel Ljunggren
Commander 2019 (C19)
• #59Rulings
The “commander tax” increases based on how many times a commander was cast from the command zone. Casting a commander from your hand doesn’t require that additional cost, and it doesn’t increase what the cost will be the next time you cast that commander from the command zone.
(wotc • 2019-08-23)
If your commander isn’t on the battlefield (or if you’re not playing the Commander variant), Sanctum of Eternity’s second ability does nothing.
(wotc • 2019-08-23)
Rulings
The “commander tax” increases based on how many times a commander was cast from the command zone. Casting a commander from your hand doesn’t require that additional cost, and it doesn’t increase what the cost will be the next time you cast that commander from the command zone.
(wotc • 2019-08-23)
If your commander isn’t on the battlefield (or if you’re not playing the Commander variant), Sanctum of Eternity’s second ability does nothing.
(wotc • 2019-08-23)