Vial Smasher's triggered ability triggers when you cast your first spell each turn, regardless of whose turn it is.

Vial Smasher has to be on the battlefield at the moment you cast your first spell. If that spell causes Vial Smasher to leave the battlefield as an additional cost to cast it, Vial Smasher's ability can't trigger. If that spell is Vial Smasher itself, Vial Smasher's ability can't trigger.

For spells with in their mana costs, use the value chosen for X to determine the spell's converted mana cost.

Vial Smasher's triggered ability resolves before the spell that caused it to trigger. If Vial Smasher's ability resolves and the spell that caused it to trigger has been countered, use that spell's converted mana cost as it last existed on the stack to determine how much damage is dealt.

The opponent to be dealt damage is chosen at random while the triggered ability is resolving. No player may take any actions between choosing the player and dealing that player damage.

If your Commander deck has two commanders, you can only include cards whose own color identities are also found in your commanders' combined color identities. If Akiri and Silas Renn are your commanders, your deck may contain cards with white, blue, black, and red in their color identity, but not green.

Both commanders start in the command zone, and the remaining 98 cards of your deck are shuffled to become your library.

To have two commanders, both must have the partner ability as the game begins. Losing the ability during the game doesn't cause either to cease to be your commander.

Once the game begins, your two commanders are tracked separately. If you cast one, you won't have to pay an additional the first time you cast the other. A player loses the game after having been dealt 21 damage from one of them, not from both of them combined. Command Beacon's effect puts one into your hand from the command zone, not both.

An effect that checks whether you control your commander is satisfied if you control one or both of your two commanders.