Y'shtola, Night's Blessed

Y'shtola's second ability checks at the moment it would trigger to see if a player lost 4 or more life this turn. If none did, the ability won't trigger at all. Once an end step begins, it's too late to cause a player to lose life in order to cause this ability to trigger.

For spells on the stack with {X} in their mana costs, use the value chosen for X to determine the spell's mana value.

Y'shtola's last ability resolves before the spell that caused it to trigger. It resolves even if that spell is countered or otherwise leaves the stack.