I agree with you, the spell description of Lulu polymorph is :
"On Enemy Cast: Polymorphs an enemy champion for 1.25/1.5/1.75/2/2.25 seconds, disabling their ability to attack or cast spells and reducing their base Movement Speed by 60."
By the League of legends official website.
Is does say disabling and by definition, it's mean :
- To deprive of capability or effectiveness, especially to impair the physical abilities of.
- Law To render legally incapable of performing an act.
By http://www.thefreedictionary.com/.
I just played against Illaoi top with Lulu and when she cast her "Test of Spirit" spell, i do polymorph and then i can't the line where the spell is cast but then grab me and pull me toward her. By definition, it should stop her action by "Disabling" her and do nothing. Kat ult does the same thing, which is clearly a bug. I think Riot should consider adding info to Lulu spell (Correct the "Disabling" word) or correct the bug.
And btw, the Stun status definition is :
The target is unable to control movement, attack or cast abilities.
By http://leagueoflegends.wikia.com/.
Which looks a lot like "Disable". If we assume Lulu polymorph cannot interrupt a spell, the Stun status should not interrupt a spell because the definition is the SAME! A Stun is a spell disable which interrupted the casted spell.
Sometimes, League of legends mechanics is confusing.