For wizard slayer you not only get spell disruption, but also cumulative 10% casting failure. Which means if you hit a mage or cleric wearing iron/stone/whatever skin, their spells will be interrupted, and with each additional successful hit the penalty will increase. However, drawbacks are also significant - no potions, no cloaks/girdles/gauntlets/rings/amulets.
You also get some magic resistance, which is handy, but Holy Avenger gives ypu better protection. Plus it dispells magic.
So, if you want a more powerful character, it is probably better go with paladin.
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Mishik's Place