When Kayn's ability says he doesn't take damage if he's moved twice this turn, how long does the damage immunity last?

Ruling: If Kayn has moved to two different locations in a turn, he won't take damage from any source (combat, spells, etc.) until the end of that turn.

Nuances:

• The "this turn" phrase refers to both the condition (moving twice) and the duration of the effect (immunity lasts until end of turn)
• The immunity applies to all damage sources once the condition is met