yeah but multitasker is too vague i'd prefer the 3 roles system
From objective distance of thinking it is impossible to classify all heroes in game in three classes you proposed(support in general meaning of word, which could be unit/hero/building support we refer as support, mass slayer, scout (which is some kind of support but not support in general), that is also roles which are equal with those you suggested in general).
Simply I said earlier that I like idea, but there is a lot "holes" in current preposition.
If we really want this in game, we must think about filling of that "holes".
Also I think it would be good for most of heroes whose role is precisely know from start, but also there is problem always because there is a lot of heroes which could have many roles at same time. And because of that you simply can't in one word describe their role in game, or get answer why they are weak or strong or have great armor or low hp. Did you know that for instance Pipin/Marry are in scout class, which could be described as some support class. And after reaching level 10 you could use them as instant damage dealers (kamikazu heroes, jump, deal damage and die if it is focused more then 2-3 sec), it is funny and ironic in same time.
Dwarven heroes are also main problem in this preposition, because all of them have many almost equal roles in same time. Most of them have great DPS(damage per second) so they kill most of other heroes with ease, also a lot of armor (even before they get mithril, after it is a show, they became semi tanks or true tanks), and at the end they have specialization, but that specialization is not something which marks them or which should tell someone who to play that hero. Best way to get some info about hero and learn proper way to play it is gameplay, that is my opinion. I know what you proposed and maybe I have gone to far, but you must always be objective when you are suggesting implementation of something.
And preposition should be referring equally to all heroes, so from my perspective when you suggest something which should be implemented partially, better is not to implement that at all. Later that causes a text bugs and similar stuff, and "hola" there is bonus job for some betatesters and ET in general.
Simply I think that current hero system is to complex so you could describe all of heroes with one word, and that is main preposition in this topic.
Also I admit and agree that it could be very useful, but in same time if this couldn't refer to all heroes equally than better not to implement at first place.
Kind regards