The EffectPolymorph() NWScript command creates an effect that will polymorph the creature it is applied to. This effect should be applied temporarily or permanently (not instantly).
Definition[]
effect EffectPolymorph (int nPolymorphSelection, int nLocked=FALSE)
int nPolymorphSelection- A POLYMORPH_TYPE_* constant indicating which form the effect will produce.
int nLocked- If FALSE (the default), players will be given a "cancel polymorph" option on their character's radial menu while this effect is applied.