Question about changing a spell's target
Hello, earlier today I was playing Commander with a group of friends. I was playing a Necron deck and managed to cast [[Shard of the Nightbringer]] targeting one of my opponents for its ETB ability, making them lose half their life points and I would have gained that much life.
They responded with [[Redirect Lightning]] to change the ability's target to me and we weren't sure of how it would work.
A quick search helped us determine that my opponent couldn't declare me as a target since it needed to target one of my opponent specifically, and not any player. However they argued that since they would be redirecting the damage, they would be the one to regain life from the second part of the effect. I think that changing the target of my permanent's ability doesn't make them their ability, therefore the part about the life gain still benefits the original spell's caster.
The table was kinda split on the subject and we tend to be very cautious about the rules because we often get confused on how precise the wording can be and how a single word may change how some spells work.
So how does this situation play out? Does changing a target also modify subsequent effects?