Strict Proctor
Creature — Spirit Cleric
Flying
Whenever a permanent entering causes a triggered ability to trigger, counter that ability unless its controller pays 
.
"You might believe being dead for centuries has made me more lenient. I think you'll find the opposite to be true."
Jokubas Uogintas
Rulings
Abilities that trigger when something else causes an ability to trigger will always go on the stack after the ability that caused them to trigger. For example, Strict Proctor’s ability will always resolve before the triggered ability that caused it to trigger does. This is a change from previous rules.
(wotc • 2021-04-16)
Triggered abilities use the word “when,” “whenever,” or “at.” They’re often written as “[Trigger condition], [effect].”
(wotc • 2021-04-16)
Effects that modify how a creature enters the battlefield are not triggered abilities and are not affected by Strict Proctor’s ability. These include (but aren’t limited to) effects that have a permanent enter the battlefield as a copy of another permanent, effects that have a permanent enter with counters, and effects that have a permanent enter tapped.
(wotc • 2021-04-16)
Rulings
Abilities that trigger when something else causes an ability to trigger will always go on the stack after the ability that caused them to trigger. For example, Strict Proctor’s ability will always resolve before the triggered ability that caused it to trigger does. This is a change from previous rules.
(wotc • 2021-04-16)
Triggered abilities use the word “when,” “whenever,” or “at.” They’re often written as “[Trigger condition], [effect].”
(wotc • 2021-04-16)
Effects that modify how a creature enters the battlefield are not triggered abilities and are not affected by Strict Proctor’s ability. These include (but aren’t limited to) effects that have a permanent enter the battlefield as a copy of another permanent, effects that have a permanent enter with counters, and effects that have a permanent enter tapped.
(wotc • 2021-04-16)