If I make a warlock villain, would giving them PC features be unbalancing, for example, pacts and invocations
AC 11 HP 115 Str 10 Dex 14 Con 12 Int 14 Wis 16 Cha 20 CR 12
Resistance to damage from spells
My party is currently 6th level and I was figuring that by level 10 they should be able to take her on as well as her 4 Acolyte minions, which are using just the standard stat block from the monster manual