Mizzium Meddler

{2}{U}Creature — Vedalken Wizard1/4

Flash (You may cast this spell any time you could cast an instant.)

When this creature enters, you may change a target of target spell or ability to this creature.

Flash. You may cast this any time you could cast an instant. · CR 702.8

If Mizzium Meddler leaves the battlefield before its ability resolves, the targets remain unchanged. (2015-06-22)
Mizzium Meddler’s triggered ability can target a spell or ability even if Mizzium Meddler wouldn’t be a legal target for that spell or ability. However, the target of that spell or ability will remain unchanged. (2015-06-22)
If changing one target of a spell or ability to Mizzium Meddler would make other targets of that spell or ability illegal, the targets remain unchanged. (2015-06-22)
The target of the spell or ability won’t change unless Mizzium Meddler fulfills all the targeting criteria. If a spell or ability has multiple targets, such as Send to Sleep, you can change only one of the targets to Mizzium Meddler. (2015-06-22)
If Mizzium Meddler’s triggered ability targets a spell or ability with no targets, nothing happens. (2015-06-22)
If the spell or ability has multiple instances of the word “target,” you choose which target you’re changing to Mizzium Meddler as Mizium Meddler’s ability resolves. (2015-06-22)
If a spell or ability has a variable number of targets, you can’t change the number of targets. (2015-06-22)