Marsh Flitter

Flying
When this creature enters, create two 1/1 black Goblin Rogue creature tokens.
Sacrifice a Goblin: This creature has base power and toughness 3/3 until end of turn.

The List

Zendikar Rising Commander

Flying
When Marsh Flitter enters the battlefield, create two 1/1 black Goblin Rogue creature tokens.
Sacrifice a Goblin: Marsh Flitter has base power and toughness 3/3 until end of turn.

Modern Masters

Flying
When Marsh Flitter enters the battlefield, put two 1/1 black Goblin Rogue creature tokens onto the battlefield.
Sacrifice a Goblin: Marsh Flitter becomes 3/3 until end of turn.

Lorwyn

Flying
When Marsh Flitter comes into play, put two 1/1 black Goblin Rogue creature tokens into play.
Sacrifice a Goblin: Marsh Flitter becomes 3/3 until end of turn.

The effect from the ability overwrites other effects that set power and/or toughness if and only if those effects existed before the ability resolved. It will not overwrite effects that modify power or toughness (whether from a static ability, counters, or a resolved spell or ability), nor will it overwrite effects that set power and toughness which come into existence after the ability resolves. Effects that switch the creature's power and toughness are always applied after any other power or toughness changing effects, including this one, regardless of the order in which they are created.