Spellsteal

[Deathlycold]

TBC-realm

Sometimes if you use Spellsteal nothing happens , no resist or immune , but it still costs mana.

[Scruffee]

Watch what you're spellstealing. Some classes have a talent that reduces the chance for that to be happening. I.E Druid Subtlety would just not give you the buff if it lands within the 30% chance.

[Pallyofhell]

same with paladins in ret which causes their seals to be immune to dispell.