Okay I haven't played Synergies, only vanilla HC, and I can tell you now, 1 point in Shadow Burst, Death's Bounty and Stone Pact won't last you long.
Heck, provided the poor Outlander and Embermage ever reach skill lvl 35.
I think people strongly underestimates the Healing provided by the bot, especially when coupled with FF; it's a godsend to HC Engineers.
Shadow Burst at +/-max, will replenish 50% of your hp with one cast, not forgetting it'll have 75/100% shield break by then.
Death's Bounty is way more powerful than you'd think.
Slow, and stun eventually, and the health AND mana has helped me out of tight spots more just a few times, especially from dot and homing missiles.
In addition, this skill renders summoner type and en masse enemie a cake walk.
Rune Vault has killed me nearly as much as it has saved me.
If surrounded, you CAN'T vault out, and this skills has a nasty tendancy to vault you into the nearest solid object. (E.g whilst going over a bridge, chances are you'll Vault into the sides) and I've used it a lot.
And back to the base 25% resist, it makes ranged Berserkers/Engineers too powerful, they technically should then have 0% too, no?
And without it, there's no way in hell you could ever make a melee/close ranged skill based Outlander/Embermage. (Shocking Burst/Arc Beam/Magma Mace/ImmoAura damage/Prismatic Rift/Glaive Sweep/Burning Glaives/Burning Leap/Bane Breath/Melee Outlander)