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Jalib, for me, is an outsider. Any normal player will simply ignore his special ability.
Demons – generally use dark magic spells.
Knights – generally use light magic spells.
Dark Elves – generally use area-of-effect spells (which, in itself, is often more effective than single-target spells).
Wood Elves – either chaos + a barrage of arrows, or general light spells.
Dwarves – either chaos + area-of-effect spells (fireball + pyrokinesis!), or general light spells.
Orcs, in theory, probably don't care, but it needs to be checked; in any case, buffs that enhance orcs, like the Call of Blood, are still relevant.
In other words, the hero's entire specialization is useless. The only justification is to use it against the Sorceress Erin (specialization: witches' sabbath) or against Svea (lightning is not deflected) and similar heroes.