Muck Drubb
Creature — Beast
Flash (You may cast this spell any time you could cast an instant.)
When Muck Drubb enters the battlefield, change the target of target spell that targets only a single creature to Muck Drubb.
Madness 
(If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)
Illustrated by
Planar Chaos#76UncommonEnglishLegality
Rulings
The spell’s target is changed to Muck Drubb only if Muck Drubb is a legal target for that spell.
If a spell targets multiple things, you can’t target it with Muck Drubb’s ability, even if only one of those targets is a creature or all but one of those targets has become illegal.
If a spell has multiple targets, but it’s targeting the same thing with all of them (such as Seeds of Strength targeting the same creature three times), you can target that spell with Muck Drubb’s ability. In that case, you change all of those targets to Muck Drubb.