Holy shit, I think I'm in love.
Implement this hero ASAP.
The portal idea is... just... epic.
But enough with the jaw breaker, now to the review:
Arcane Blast: Good Nuke, nice gank tool when ult is up, and a decent farm ability even with no charges and could be very spamable when suficient mana is available (bloodstone FTW). Small AOE, but with perfection, you'll never miss a blast. The thing is: those 0.3 seconds delay for the blast, they have an animation? Because, with that tiny AOE, animation for the pre-blast would just make the enemy hero clink once, and he'll be most likely safe. Maybe increase the AOE for a very small amout with the ult, or make it an instanst cast abillity. The effect I imagine for this one is like a Pugna's Nether Blast, but white or grey.
Arcane Dome: So, what would the effect of this be? A grey, flatter chronosphere maybe? Can really fuck up with Sniper, Mirana and ranged DPS's in a team battle, while your cooldowns are recharging. The knockback, as you said, can fuck up Lycan and alike, and also send some enemy heroes to a cliff, or make them unable to reach a tower, while you, with no problem whatsoever, deny the tower. Nice "pseudo-chanelling" concept, you can attack and move, but not cast spells.
Arcane Discontinuity: Nice juking, gank, or support skill. Can be used in many ways, like linking the ground to a cliff and stay there on top damaging a melee enemy hero, or to surprise assault and enemy team in Roshan. The 10% damage for foes who use the portal is it magical damage, or direct HP removal? Does the portal gives True Sight and flying vision for the area and duration? I think that an average flying vision (about 500-550 range from the center of the portals) on both the portals could be nice, you know. Also, any ideia on the collision size, and model size for the portals? The effect for this could be that portal that is available on the World Editor of the Frozen Throne. Originally, it's a purple portal with 5 dots on it's sides. Take the model, reduce it's size and turn it grey-like.
Empower: Maybe it could increase the AOE for the Arcane Blast on bigger levels of the ult too. Also, let's analize something, Rubicks Null Field magic reduction is 5%, 10%, 15% and 20% on 900 AOE on lvls 1, 2, 3 and for respectively, while Aenor's magic reduction with Arcane Dome and ult reduction is 24%, 32%, 40% and 48%. Even being on only 300 to 360 AOE, it's a bit too much. Imagine, if a Lich ult's, and on the delay that the ult's projectile takes to arrive to an average range an Aenor casts Ult and Arcane Dome, on the targeted party, most of the Lich's ult will be denied. Kind of Imba. As for the portal blast, pretty good, a nice way to kill that persky runaway on red health hero. Maybe in addition with the lower cooldown and no mana requirement with the Agha upgrade, it could, when cast, allows a greater cast range for the other spells. Effect for the ult: just like when Furion has an Agha, add the "rays" to Aenor's hand, but grey. Effects for this skill with Agha: Maybe an aura beneath him, or something like glowing scepter or amor.
Also, I would love to add the link of the hero into my Steam Account, but how do I add myself a signature?
With great emthusyasm to play with this character, http://steamcommunity.com/profiles/76561198047111600