User blog comment:Willbachbakal/(Item Concept) A New Kind of Crit/@comment-24385282-20150705203043

Does switching targets remove the critical strike mark? What happens when 2 champions with critical strike chance attack the same target? What if they're from opposite teams, attacking a neutral monster?

Also I can pretty much guess that your proposed additions of critical strike marks per damage tick on abilities such as Malefic Visions and pets such as Voidlings would make AD Malzahar insanely OP. With Infinity Edge and nothing else, Malefic Visions deals 278 at rank 1, and that's with no other items and no more ranks put into the ability. Malefic Visions will critically strike 4 times, or 5 during its duration with the assistance of a single Voidling - which will be dealing 80 damage per attack. Overall, with a single Voidling, a single item, and a single rank in Malefic Visions, Malzahar will deal 486 without using a basic attack. Realistically, he'd have around 2 Voidlings out at almost all times in combat, be using basic attacks, and have more ranks in Malefic Visions. When using Nether Grasp and Null Zone, that adds 4 more critical strikes along with those abilities' base damages.

So, if AD Malzahar has 2 Voidlings (before Grow or Frenzy) out, uses a combo of Malefic Visions [Rank 5], Null Zone [Rank 1], and Nether Grasp [Rank 1], and has Infinity Edge and nothing else, and doesn't even use a single basic attack or Call of the Void [Rank 2], he'll critically strike 10 times and deal 1550(+4% target's maximum health) damage in 4 seconds.

Compare that to a Katarina with basically the same thing. If she uses a full combo of Bouncing Blades [Rank 5], Shunpo [Rank 1], Sinister Steel [Rank 2], and Death Lotus [Rank 1], and has a Rabadon's Deathcap and nothing else, she'd deal 1262 damage in ~3 seconds.

Or, if you compare it to AP Malzahar with the same statistics, combo, etc. as the AD Malzahar except with Rabadon's Deathcap instead of Infinity Edge, even giving him the benefit of also using Call of the Void [Rank 2], which AD Malzahar completely skipped out on even though he put another point into it for some reason, he'd only deal 1417(5% target's maximum health) damage in ~4.25 (extra Q cast time) seconds. Though they would deal the same damage if their target had, say, 13300 health.

After the math, no, he's not completely broken as AD with the proposed rework. But he's clearly designed to be AP so I think he should be doing more damage with an AP build than an AD one.