How long did you wait after using Curse? You should cast Curse a few times in a row, then cast Polymorph, all within about 5 seconds.
Curse
Curse your enemies and let them suffer your wrath. To use, make the skill your active skill, and right click on your enemy.
Level 1 Targeted creature loses 5 percent offence and 5 percent defence. Resistances of targeted creature are lowered by 5 percent. Curse lasts 5 time units.
Required level is 12. Magic cost is 12.
Level 2 Targeted creature loses 5 percent offence and 5 percent defence. Resistances of targeted creature are lowered by 10 percent. Curse lasts 5 time units.
Required level is 16. Magic cost is 14.
Level 3 Targeted creature loses 10 percent offence and 10 percent defence. Resistances of targeted creature are lowered by 15 percent. Curse lasts 10 time units.
Required level is 20. Magic cost is 16.
Level 4 Targeted creature loses 10 percent offence and 10 percent defence. Resistances of targeted creature are lowered by 20 percent. Curse lasts 10 time units.
Required level is 24. Magic cost is 18.
Level 5 Targeted creature loses 15 percent offence and 15 percent defence. Resistances of targeted creature are lowered by 25 percent. Curse lasts 15 time units.
Required level is 28. Magic cost is 20.
