Cloud spell - Attacks Prevented

Melee
Ranged
Special // what are special attacks?
Spells

Possibly stuff like ensnare.

Why is esnare special?

Special spells maybe spells that don't check for Spell Immunity, like Web (which can be toggled on/off in Game Constants). They might be, I'm not sure.

what is the id of ensnare if it's a spell ?

Ensnare is an ability, but is not a spell. Non-spell abilities ignore magic immunity (without being ultimates), and can be cast while silenced.

Ensnare == what ? ('xxxx')

EDIT : Ensnare == 'Aens' (thx War3x.mpq\Units\AbilityData.slk)

and there is also 'ANen' for passive neutral and 'ACen' for hostile neutral