Fleshformer — ruling 1

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.

Fleshformer — ruling 2

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 : règles, fonctionnement et interactions (MTG)

Fleshformer is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

: This creature gets +2/+2 and gains fear until end of turn. Target creature gets -2/-2 until end of turn. Activate only during your turn. (A creature with fear can't be blocked except by artifact creatures and/or black creatures.)

How it works : Fleshformer

Original English text — Wizards of the Coast / Scryfall

#1February 1, 2009· Wizards of the Coast
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.
No other card is named in this ruling.
#2February 1, 2009· Wizards of the Coast
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.)
No other card is named in this ruling.