Spell penetration as udk in pvp/arenas yes or no?

So in general spell penetration is needed in pvp or not? I got different opinions and there are different guides, how is it on warmane? Gem spell penetration or just stack strength?

Thank you in advance

https://forum.warmane.com/showthread.php?t=320716 found this ty all

Quote:

---

Originally Posted by Chillittar

So in general spell penetration is needed in pvp or not? I got different opinions and there are different guides, how is it on warmane? Gem spell penetration or just stack strength?

Thank you in advance

---

135 spell pen