So I'm playing a mage,
Wise choice.
but I've noticed a LOT of critters, especially some of the high dragons are annoyingly immune to fire damage. As a result, I want to make two staves, one with electrical dmg, one with cold.
I would actually recommend three, if you have the patience for it.
One with fire base and spirit rune to combat electrical dragons.
One with cold base and dragonslaying rune to combat fire dragons.
This is really all you need right here, but the third...
One with electrical base and corrupting rune for ice dragons. Then after all ice dragons are dead, replace the corrupting rune with a cleansing rune or dragonslaying rune for the Red Lyrium Dragon.
The ice dragons are the weakest by far, and electricity/corrupt or fire/spirit should be all you really need for them.
I'm thinking I should incorporate either a Spirit rune, a dragon-hurting rune, or a living-critter-hurting rune.
I think all three do damage, but spirit only really does well against electricity dragons. And I don't think corruption does anything against the Red Lyrium Dragon. The dragonslaying runes work well for all dragons. The only time you'd use something else is if they have a weakness to something. Like the electricity dragons having a weakness to spirit runes. Dragon slayer runes are basically for dragons that have no obvious weaknesses, or where the weaknesses don't matter much to winning the fight, like with the ice dragons.
My question is this, are there any staves in game or that I can make that are better than what I'm using now?
My current staff is one I crafted:
Resolute Imbued Scepter
201 DPS
92 Fire dmg.
+32 vs. Living (from a Master Corrupting Rune)
+27% Barrier dmg.
+28% Critical dmg.
+9 Magic
+9 Willpower
Probably. One thing that stands out right away is that you only have a Master Corrupting Rune. There is such a thing as a "Superb" tier of rune above the "Master" tier. I don't remember if the corruption class is among them though. But I think a Superb Dragonslaying Rune would be better. I think it gives +50 damage vs dragons. And corruption won't work on the Red Lyrium Dragon.
Another problem I see is you are wasting your time with barrier damage. Dragons don't use barriers (the blue bar). Some use guard (the grey/white blocks). But I wouldn't bother making a staff with guard breaking ability either. Let your warriors smash guard with Shield Bash and such, or use the alternate Stone Fist ability. Unless of course you are playing a solo mage.
Willpower is a waste. It only increases your mana pool. Not that important for long fights. Basically, you should just have enough willpower to cast two spells from a full bar of mana. For example, Barrier and Energy Barrage. Then wait to recover mana. Having spell passives that allow for faster mana recovery is the better option. Like the alternate Fade Step ability that replenishes mana instead of inflicting frost damage. Increasing willpower won't do much except cut down on how long you have to wait before casting another spell.
I think with dragons you should try to focus more on critical damage and critical chance. This is so you can damage their limbs faster, leading to them wincing in pain for a few moments and eventually falling down until they can recover. Magic is fine for a mage, since it increases damage.
Look for the best schematics possible. I'm not sure if your staff design is better or worse, but there might be a better design and material than 92 base damage. Not sure though. I'd have to look.