I think Demon has a lot of potential and so many viable builds that we will see him very often either as enemy or as an ally.
Great work GPG!
Cant wait to see him in action!
I dont see this demigod having any strong builds for any kind of compeditive 2vs2 (or 3vs3, could be wrong about 3vs3), no stuns and TB or reg squishyness without range to kite.
With the long cooldowns generals easilly recover a lot of the damage done in that time (i do assume that DA is not able to win mele 1vs1 fight without starting with better health/mana %s). I really dont see him being able to hold a lane.
None of his abilitys help allies out (shadow may allow more ganks) apart from added burst damage, unless he starts of with TB (with Ice bonus) AA dps. with no stuns, no buffs/debuffs the only way DA is able to contribute to 2vs2 or higer fights is to get in and do mele damage wich he is too squishy for (you could possibly health stack with him like ub to make this not a problem).
I assume this is what the beta is for: adding an interupt or snare to Warp Strike, or making his stat boost an aura (they are rather underpowered compared to other demigods stat boosts) would start to make him scary and more useful than an over specialised ganker (though with no stuns currently, unless you are stupidly brave vs him you can always tele out).