The volatile staff spec damage needs to scale with Magic level. It might be somewhat balanced in the high-lvl combat brackets where you have ags and ballista to compete, but it's honestly broken at lower brackets. With 75 Magic, 1 Def, 70 HP and 31 Prayer, wearing the volatile staff (my +1 item), occult and MA2 cape only I'm able to hit 73s, with potential of hitting another one 5 ticks later. That's a cb lvl of 57. Tell me how melee and ranged can hit 70s in that cb bracket. It can also easily be stacked with 1 gmaul spec, hitting up to 100 damage in a single tick.
The damage formula could be somthing like Magic/2 + 6, so base max hit is 44 damage with 76 Magic (max 55 with the setup above), 55 damage with 99 Magic, or 60 damage with 109 Magic (imbued heart, a 20m item).
I also think the harmonised staff is too good in PvP because trident can be used at all here. It's 25% better dps than previous 5-tick fire spells which already were the highest single-target dps spells. With 75 Magic and staff+occult+MA2 cape I can hit up to 37 every 4 tick with fire wave, or up to 45 with 95 Magic and fire surge while maintaining a very low combat level.
All this is because mage unlocks most of it's full power early on, with 95 Magic, 75 HP and 1 Def (> 70 cb lvl) you have access to every spell you care about and +32% magic damage bonus gear out of +38% in total. Melee and range have a much steadier progression where damage-boosting gear like bandos and void have higher reqs to wield.
EDIT:
A damage formula that scales with Magic level have now been added to the Volatile & Eldricht staves. They didn't specify any details about this formula, so I tested them in the POH to see what the new max hit was for each magic level. The numbers below are the base max hits without counting the staff's built-in magic damage. Magic potions and imbued heart DO raise your max hit, however the damage is capped at 99 Magic.
Volatile Staff
75 Magic - Base max hit of 44 (max 55 with staff+occult+MA2 cape)
80 Magic - Base max hit of 47 (max 59 with staff+occult+MA2 cape)
85 Magic - Base max hit of 50 (max 63 with staff+occult+MA2 cape)
90 Magic - Base max hit of 53 (max 67 with staff+occult+MA2 cape)
95 Magic - Base max hit of 56 (max 71 with staff+occult+MA2 cape)
99 Magic - Base max hit of 58 (max 73 with staff+occult+MA2 cape)
So you get about 3 max hits every 5 levels with a gradual increase in between. This seems good to me as the biggest problem was at lower combat brackets. 75 Magic is still its only req, but it seems they wanna add a 50 HP req in addition. All these are good changes imo. Also barely tested the Eldricht Staff which seem to follow the same pattern: Base 34 damage with 75 Magic, and base 44 damage with 99 Magic, also here it's capped at 99 Magic.