This is another case of "it's a special ability, not a spell". Ophidians are immune against spells, but Beguile is a special ability. This isn't made properly clear, though, and should be rectified. There are a lot of special abilities, that, at first glance, could be considered spells. Despair and Coal Stones, for example.

That is what I'm talking about, but maybe I wasn't expressing myself properly again. There are lot of abilities that common sense would dictate are spells, but are implemented as special abilities. Magic Immunity, however, doesn't care about common sense, only what the xml says. If something is implemented as special ability, Magic Immunity won't work.

Stardock should either turn those spell-like abilities into real spells (with a mana-cost of zero) or clearly label them as special abilities, so confusions and immersion breakers like this won't happen.

Yeah Im going to change this so that magic immune makes you immune to all spells/abiltiies.  The only abilities that are on the edge (that i could imagine a resistance chance for even if you are immune to magic) are Stun and Tangled Web and I think its just easier to have magic immunity make you immune to those as well.

That should up their deadliness rating, I think, if they're immune even to Tangled Web and skills like Stun.  I am kind of curious if they are also immune to terrain-area spells like Stinking Mud?

They are only resistable to things that can be resisted (hurl boulder and poison damage can't be resisted).