Heroes can equip shard which give them alternative abilitys or modify existing ones. Before the shard update there was a major abuse possible that skills and abilitys scaled hard with critical damage. This was specialy the case when the player reduced the Hero Damage of an hero to nearly zero, because the Crit scaling will be dimished if the Hero damage is increased. The solution to the problem was to cap out crit scaling to the Ability power and Hero damage a Hero has. I belive (don't know) that this is what the system  was like. 

Currently the skills of heroes stoll have this cap in place, but since alot skills and abilitys moved from heroes and weapons to shard, it is possible again to raise the crit by reducing the Hero Damage. This leads to that ANY shard for Heroes which scales of AP/HP/HD can crit with millions if not billions of damage by reducing the damage to nearly down to Zero.

Steps to reproduce:

• start the game
• equip any hero with any shard which gives an special ability or modifies an ability (e.g. Monk Harbinger pole smash, squire betsy sword beam, or simple quake for boots, any damaging skill from shards)
• reduce your hero damage to nearly 0, or as low as you can
• increase your crit chance as high as you can
• start hitting something and notice X-XXX millions of damage

Expected result:

The shard skills and modified skills also have caps in place or at last a better crit scale solution. It is not rewarding at all that crit gets lower when atk gets higher and crit gets higher when atk gets lower. The whole system still is a mess in my eyes.