Until end of turn, target creature you control becomes a green Wurm with base power and toughness 6/4.
Overload {4}{G}{G} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")
Because a spell with overload doesn’t target when its overload cost is paid, it may affect permanents with protection from the appropriate color.
Effects that modify the affected creatures’ power or toughness (such as the effects of Force of Virtue or Giant Growth) will apply no matter when they started to take effect. The same is true for counters that change the creatures’ power or toughness (such as +1/+1 counters).
If you don’t pay the overload cost of a spell, that spell will have a single target. If you pay the overload cost, the spell won’t have any targets.
Scale Up overwrites all previous effects that set the affected creatures’ color, creature types, power, and/or toughness to specific values. Other effects that set these characteristics to specific values that start to apply after Scale Up resolves will overwrite that part of the effect.
The affected creatures don’t lose any abilities when they become Wurms.