Knockback

This gem is very weak because the knockback distance is very short. If the chance of knockback was higher and the knockback more noticeable, it might be more useful. Right now it's a waste of a socket.

More a mechanics question than a question directly related to this skill, but this seemed the most likely place to yield an answer...

Is base knockback a flat value, or do crits (or higher damage attacks in general) knock back farther than non-crits?

I like the idea of a knockback support gem, but this just doesn't pull its weight. It doesn't really make much of a difference knocking mobs back, the distance is much too short to be worth the support slot.

Also, it doesn't knock them farther away on crits, which for some reason seems unintuitive. I think the amount of knockback needs to be increased to about 250% of its current distance, and the distance knocked back on criticals doubled. To make sure this isn't overpowered on fast-hitting builds mobs would need some kind of knockback resistance that builds up each time they are knocked back, reducing the distance of future knockbacks for a few seconds, stacking until it wears off (like a 2 second buff).

The only time I got good results out of knockback was on a super-fast-attack ranger with knockback, faster attacks and added cold damage. When I attacked a single target repeatedly I'd chill it and get enough knockbacks to keep it away (most of the time), but I still think I'd rather have more damage or more utility (pierce/mana cost redux/imp aoe etc) over this particular gem.

I am using cleave on my dual Rapier ranger as a Mass kill/crowd control ability , so added to it Cold gem and blind. Recently found this one, this gem make wonders in addition to the chill/frozen and blinded enemies giving me addiional edge against hard hitting mages <3

Critical strikes with knock back should cause an improvement.

I'm using this configuration and it's good. I've got two totems casting firestorm on enemies cursed by temporal chains and elemental weakness. They try to approach the totems but the knockback effect keeps them away. Assumed that every fireball hits an enemy (not always correct) I have 8 fireball every 1,2 seconds * 2 totem = 16 fireball every 1,2 seconds with 40% knockback = 6 or 7 fireball knocking back multiple (?) enemies every 1,2 seconds with 1 second required between each cast.

Maybe increase Knockback by 2% for every 1% of target hitpoints taken by the attack?
That would increase knockback on strong attacks;
Otherwise it's really only useable on very fast attacks, say, freezing pulse+Cast speed, or the above.

Adding knock back to freezing pulse would be... well, stupid. Don't do it :)