Do Thousand Tailed Watcher's might reduction and similar effects apply to units that enter play after the effect resolves, and does the reduction continue to apply if a unit gains might later?

Ruling: Thousand Tailed Watcher and similar might reduction effects (Smokescreen, Stupefy, Ahri BS) "snapshot" when they resolve - they apply once and then stop. Units that enter play after the effect resolves are not affected, and units that already had the reduction applied can gain might afterward without the reduction reapplying.

Sequence:

• When Watcher's effect resolves, it reduces the might of all units currently in play by 3
• The effect then stops looking at the game state
• Any units played afterward (like Shen as a reaction after Watcher's effect has resolved) do not get the -3 reduction
• If a unit that was reduced later gains might through other effects, it gains the full amount without the reduction reapplying

Nuances:

• If Shen is played as a reaction to Watcher being played (before Watcher's WYPM effect resolves), Shen enters first and would get the -3 reduction
• If Shen is played after Watcher's WYPM effect has already resolved, Shen does not get the reduction
• Passive effects with "while" text work differently than "when" or "give" effects - passive effects continuously apply
• Battlefield passive bonuses are calculated in the arithmetic layer before subtractions, so a unit at a +1 might battlefield would be at 2 might when Watcher resolves, then reduced to 1 might (base 0, +1 from battlefield)
• These are not "debuffs" - buffs are a protected term in Riftbound relating to specific deck archetypes