Yes, only the qualifying stun, might decrease, or return-to-hand event is replaced; the spell or ability's other instructions continue unless a later linked instruction specifically requires the replaced action to have occurred.359.3.e.14.b A replacement effect only replaces the specific event or instruction that qualifies for it.370.1370.1.b
Example
You play Star-Crossed, targeting your own [Empowered] Gangplank as the friendly unit and an opponent's Elder Dragon as the enemy unit.
Gangplank's replacement effect does not apply to the separate return event affecting Elder Dragon, so Elder Dragon returns to its owner's hand normally. Returning Gangplank is the qualifying event: instead of going to hand, he gets +3 this turn. The rest of Star-Crossed resolves normally; it simply produces a different result for the one return event involving Gangplank.
When Switcheroo would decrease an [Empowered] Gangplank's might, Gangplank gets +3 this turn instead, while the increase affecting the other unit remains unchanged. Switcheroo chooses Gangplank when the spell is finalized.355.5355.10 When it resolves, Switcheroo first determines one difference, then creates separate might-increase and might-decrease effects for that fixed amount; replacing one does not recalculate or alter the other.434.1.a434.1.b434.1.d Gangplank's replacement effect replaces the decrease affecting him because it comes from a spell that chose him, but an increase does not match any event his ability replaces and applies normally.370.1370.1.b
Example
An [Empowered] Gangplank with 6 is swapped with a Determined Sentry with 1 at the same battlefield via Switcheroo.
The swap action calculates a difference of 5, then creates two effects: -5 for Gangplank and +5 for Determined Sentry. Gangplank's replacement effect replaces the -5 decrease affecting him with +3 this turn. The +5 effect applies only to Determined Sentry, so Gangplank's replacement effect does not affect it.
After Switcheroo resolves, Gangplank has 9, and Determined Sentry has 6.
From Riftbound FAQ by Christian “Near” Ivicevic, licensed CC BY-SA 4.0.
Reviewed against Core Rules 1.5. Unofficial; not from Riot Games.
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