Change Abyssal's passive to a defensive one.

Right now, If you are in an AP vs AP lane, Abyssal rush is mandatory. If you go Morellonomicon vs Abyssal, you simply get bursted while he can facetank your burst easily. In my mind, you should go Abyssal if you dont want to get insta-bursted, but the tradeoff being you won't oneshot the enemy laner either. My suggestion for a new passive is this:

• UNIQUE: For every 10 % missing HP, gain 3 Magic Resist

This would potentially grant you a whopping 87 MR when you are at 10 % HP, The numbers might need tuning so it becomes like:

• vs = the laners barely scratch each other
• vs = both laners trade evenly (if they both hit their spells OfC) but no 100-0
• vs = The laners can basically oneshot each other

and Morello would obviously give way more damage in early teamfights - both from AP and CDR.