Encounter Conditions are triggered on either a Critical Hit or a roll of maximum damage.
Defender makes a Constitution saving throw, DC = 12 or half damage received, whichever is higher. On failure, defender suffers Encounter Condition, depending on damage type. Creatures that are immune or resistant to damage types always succeed on saving throw.
At the end of the creature's turn, they make a DC 12 saving throw, ability as specific by the Encounter Condition
All Encounter Conditions end with the end of the encounter.