Black Hole - a rune that has the effect: for the duration of the skill, enemies closer to the center of the black hole have their movement speed reduced more than those on the outside...since it's gravity and all y'know? Maybe that should just be a base characteristic of the spell.
^^ Supernova rune - enemies are drawn in by a collapse of gravity, and then exploded outward?
^^Quasar rune - since they're the biggest and baddest things in the universe, maybe make the black hole emit gamma rays in 2 opposite directions (180 degrees apart) that does an insane amount of damage, a la real life. <3 physics
Spectral blades - a rune that increases attack speed with a number of stacks, so that you can slice and dice enemies all ninja-like
Electrocute/shock pulse - since their both lightning like... i'd like to see one of the runes turn it to more of a lightning or chain lightning a la diablo 2 style. (i know, i know... you're obsessed with not comparing d2 to d3 and keeping it A SEPARATE GAME COMPLETELY!!1!. But you did it with frozen orb so this isn't a stretch.)
^or alternatively, what about a chain-nova type thing? enemies hit by the nova have a chance of creating a nova themselves.
Disintegrate - a rune that allows disintegrate to go through obstacles, so that you can stand in a safe place and burn it up. I think that would be cooler than some of the current runes
Flame Blades - maybe make this change the graphic to a single bigger fiery blade like a flame sword. maybe make it set enemies on fire to burn for a high amount of damage for a short time?
Arcane orbit - I think this has been underwhelming for awhile, maybe give it a small pushback to keep enemies away from you at least?
Blizzard - Glacier rune - turn the blizzards into larger ice blocks that have a chance to stun the enemies?
Magic weapon - I can't remember right now, but isn't there a fire rune? Shouldn't that be called Enchant? D2 or D1 references are noooot a bad thing! They integrate D3 into the franchise even more and make things seem more connected, while giving people a positive reminiscent feeling. You've done enough to make D3 not D2 v2.0... but I feel like you should connect things when possible.
I understand some of these would require graphics changes to the skills themselves instead of palette changes, and that's extra work that might not fit in the scope of the expansion. But I think that visually pleasing effects are critical to how an effect feels. Instead of taking the (short-sighted imo) approach of keeping the skill looking the same all the time, the more you can change it by runes in effect makes it more like a new skill altogether. This adds tons more character and visual satisfaction for the player. Take sleet storm for example, it's a whole nother animal compared to the base Ray of Frost. Please discuss and consider this approach for RoS or beyond it.
Just some of my thoughts, I apologize if it's not posted in the right place, and I encourage others to share ideas as well since...now is the time for suggestions before RoS is finalized. I do like the direction D3 is headed, Thanks!