Disruptor is part of his identity, admitted.
But I still stay to my comment that he has assassin mixed in.
The play pattern is just way to similar to it. Just because he isn't deleting someone with damage doesn't mean that he can't have the playstyle of an assassin.
So he actually is a mix of all 3.
He has the shield and healing of an enchanter, the lockdown and area denial of a disruptor and the mobility of an assassin.
To show what I mean: Here is the definition of a disruptor given by Riot themselves.
We initially called this subclass ‘control mages’ but realized that could be expanded to the entire group (that and ‘Utility Mage’ wasn’t a very good Class name). Disruptors specialize in locking down opponents or, in some cases, entire battlefields by creating intense zones of threat that only foolish enemies would dare wade through. Although not as reliant on their friends as Enchanters, the fragile and immobile Disruptors greatly benefit from allied presence - both to deter incoming danger and to help capitalize on targets they’ve locked down.
His ability to escape alot of situations with his mobility qualifies him for me as partly assassin.
And let's not forget his reveal. Riot themselves stated that he is much like an assassin.
Much like an assassin, Rakan waits for the perfect moment to explode on the scene and charm the pants off the enemy team.
[...]
Again, like assassins, Rakan's in for a bad time if the bad guys manage to collar him with hard crowd control.
So to deny that he has assassin mixed in when even Riot themselves state all the similarities.....