Malzahar Ability Cooldown

So apparently Malzahar has a new Ability, which, after a period of taking no damage, allows him to reduce all inbound damage by 90% for roughly 0.5s. The issue is not the reduction value, its actually the cooldown at later levels, going as low as 4s at Lv 18.

I think the cooldown for something as powerful as free damage reduction should be a flat 20s, but scales with CDR so that it can synergize with the standard "ready for anything" playstyle.