I can't decide what would best fit in the last two slots. I've contemplated diamond skin - prism and critical mass, which would increase survivability slightly and decrease the time I spend not using arcane torrent, but I'm not sure how the damage absorption will apply in relation to the force armor rune in energy armor.

I've also considered temporal flux as a passive, and adding some tertiary source of arcane damage, but I don't think I really want to split my attention between two main damage spells. Another reason against this is simply that this build is slightly lacking in defensive capabilities.

Yet another option I've considered is using slow time as an active skill, and slotting the time warp skill, which increases damage dealt to enemies in the bubble. I would likely choose critical mass in conjunction therewith, so as to increase the uptime of the damage buff from slow time, but another thing to consider is that, in such a situation, slow time would be my only ability with a cooldown, and therefore I would not be getting the full value from critical mass.

However, to explain the parts of the build which are already chosen, I have selected spectral blade with siphoning blade because spectral blade itself has a relatively high damage output when compared with other signature spells, and siphoning blade is preferred to the other runes available for that skill simply because spectral blade would only be used whenever I lack the arcane power required for arcane torrent.

I choose hydra with arcane hydra because it is a standing, low maintenance damage source which would benefit from the arcane damage bonus given by arcane torrent's disruption rune (15% for 6 seconds after the target is hit by arcane torrent)

Energy armor has, admittedly, little to do with the previously mention skills, but it is exceedingly valuable when considered in conjunction with my plans for my character. Force armor, which limits the damage of any hit dealt to me to a maximum of 35% of my maximum health, is more than meets the eye. If I equip my character with little or no extra armor or resistances, and stack on ridiculous amounts of life regeneration, then I will simply heal myself more quickly than the 35% of my health that any given hit can deal. Imagine, 3,000 maximum health and 6,000 life per second. 35% of my health being exactly 1050 damage, creatures would have to hit me more than six times per second to overpower my regeneration. Realistically, however, there is the slight chance that four creatures will simply hit me simultaneously, but my character's freedom to stack dps instead of defenses should hopefully take care of the vast majority of mobs.

Any thoughts?