Barbarian
Leap Attack: Speed of the leap is affected by FRW and jumps straight forward at long range instead of a slow leap through the air on a short distance. Damage remains low, but acts as a replacement for teleport (can’t go though walls though)
Weapon masteries: Damage stays the same but each level gives a small amount of area damage to improve clear speed.
Druid
Firestorm: No longer split into random paths but instead is released as a single fast moving line of fire that is 2-3 yards wide and 8 yards long.
Molten Boulder: Rolls faster and explodes at the end.
Volcano: No longer shoots balls of fire at random but release 6 consecutive balls of fire in a circle.
Armageddon: Rains fire and reduces enemy resistance to fire.
Necromancer
Bone Spirit/Bone Spear/Teeth: No longer requires Bone Prison in the synergies and has increased damage equal to the max lvl bonus dmg of Bone Prison.
Skeleton Mage: At max level each mage has a Bone Armor around them
Assassin
Blade Fury: Damage buff and increase area of effect on the blade’s path. Increased attack speed improves the speed at which the blade travel and the rate at which you can throw.
Blade Sentinel(s): Throw two spinning blades with crisscrossing paths. Increased attack speed improves the speed at which the blade travel and the rate at which you can throw.
Martial Arts tab: Honestly, almost everything there deserves to be reworked in some way or another.
Not sure I get that first one at all. BP isn’t required…or do you mean “no longer includes” instead? Either way I’m not sure why you’re suggesting this. Prison and Wall both synergize to defense (Bone Armor) and offense (Teeth/Spear/Spirit), as well as being useful skills in their own right. Why remove that?
Mages with armor, meh. They’re still fragile and stupid and unsummon themselves at random. Armor won’t change that. 
I get the feeling the recommendation is to remove the synergies and buff the original three to the strength level of spending the points on the other synergies. That would leave you an extra 20 pts to allocate to thing like revives and CE. I think bone spells are strong enough before you give them an army of revives and a better CE.
Giving mages bone armor does nothing to improve them. They need a mastery of their element that kicks in at higher levels. Poison needs the duration massively shortened.
Blade fury is pretty strong. It just needs the AR demands to be less. You basically need a Blessed aim merc if you want to run blade fury.
I proposed that in another thread but I received backlash because apparently that’s going too far lol I was trying to find a little workaround to lessen the blow while still making the mages sturdier.
I did a test run in single player at some point and I found it underwhelming even with an inventory full of charms and perfect gear. My idea with the assassin was to make blade sentinel better at dealing with large packs and blade fury better at getting rid of super uniques and bosses.
Pretty much, I personally hate single element builds when it comes to immunes and I always hated how slow the bone necromancer can be in PVE when doing anything else than targeting unique monsters only. Having more points for CE would make dealing a pack of monsters more enjoyable.
OK, in that case I’d say why take out Prison when Wall is clearly an inferior skill? Take Wall out of the synergies instead, Prison is just too useful.
I kind of like the Leap idea with its speed being affected by FRW, but I bet that would be tricky to code without reworking the skill’s base function. As for the masteries they should be condensed because there are too many. Compress them down into 1H weapons mastery, 2H weapons mastery and dual-wield mastery instead of the current “one for each weapon type” which really limits how many points people are willing to spend there.
Honestly if they fixed summons randomly disappearing, they would become a whole lot more viable.
I would like them to re work the assassin MA elemental claw skills.
Give them a damage increase and get rid of the charge system.
Some ideas
Leap attack
Hit with 5 yard circle, scale with all physical attack source.
Anyone hit are stun for 3sec.
Each level increase Radius and damage scaling.
Rationale: this make leap attack a viable build ( like D3) or a good close in skill with crowd control.
Freezing arrow/ explosive
All cold/ fire damage sources exploded in a radius.
Increase size of radius per level ( or per few level). Add flat damage per level
Synergy skills:
Convert physical damage to additional cold/fire damage.
Increase scaling per level. Increase %damage per level
Rationale: Impove the much needed damage and AoE. The pierce part maybe reduce radius or something. Looking for flat elemental damage jewels and charm add to the fun, instead of everyone go for skilled charms.
Zeal/fury/ frenzy and other single target melee attack.
Hit with a 5 yard ( invisible?) radius . Help with much need trash mobs
Some AoE but not too big to not feel like melee.
Melee attack can ( optional, hold shift or something) charge to next target within 15 yards ( ala wolcen) with 4 sec internal cool down.