Moldeacarne

Fleshformer can target itself with its ability. The result is that Fleshformer gains fear, since the +2/+2 and -2/-2 parts of the effect will balance each other out. (Fleshformer's power and toughness will each momentarily go up by 2, in case anything cares about that.)

Fleshformer's ability has only one target: the creature. If that creature becomes an illegal target by the time Fleshformer's ability would resolve, the entire ability doesn't resolve. Fleshformer won't get +2/+2 and won't gain fear.