The current GvG/HA metas are stupidly broken (especially GvG). Hexways dominate everywhere, which are damn hard to beat if the team doing it well. In HA (almost) only smiteways can be seen, with at LEAST one Me/Rt and Tease.
Palm strike sins are everywhere, they fit in any builds with their godly spammable snare and deadly chain (cripple every 4 sec??!?!!? wtf).
Now lets see.
Skill balance
Many skills have to be rechecked, but here are a few ideas.
Lingering Curse: -20% healing instead of -33%, OR affects only targeted foe and not adjacent. Still useful, but doesnt rape the whole party heal stuff which is kinda the best counter vs hexways.
Palm Strike: reduce dmg to 10...60, activation time to 1 sec, recharge to 8 or 10 sec. It would make other elites more useful like wastrels collapse etc.
Visions of Regret: reduce dmg to 5..65 or something like that (not so often used now, because of the bad balance of necros)
Wastrels Worry: reduce dmg to 20..65 OR add a normal recharge for this skill
Hundred Blades: only deals the bonus damage if you actually HIT with your sword (so blind, block and stuff can counter it)
Smiteways.
Thats more like a HA problem, but they can be seen in GvG as well.
The best solution would be to simply remove all heroes from HA and GvG, but that will never happen.
Heroes with Tease are just plain annoying, only because of that I suggest a nerf to Tease as well.
Currently: If target foe is using a skill, that foe and all foes in the area are interrupted and you steal 0...4 Energy from each interrupted foe.
Update it to: If target foe is using a skill, that foe and all adjacent foes are interrupted and you steal 0...3 Energy from each interrupted foe.
And the worst thing ever. Me/Rt-s with fast cast weapons. The best thing would be a mechanic change (although thats pretty hard), remove the fast cast effect from wep spells. If anyone have a better idea for this, you are welcome

Discuss, post your thoughts, if you have any other ideas I'll probably quote in the op.
Edit: Mark of Insecurity : drop duration to 4..10 sec (so its still useful for spikes), 10 nrg, maybe 15 recharge but its not that necessary.