Corrupting Potion : Abilities and basic attacks apply a burn that damages enemy champions for 15 - 30 (based on level) bonus magic damage over 3 seconds. Bonus damage is halved for area of effect and damage over time effects.

Morgana Q -
Scorch
Your first ability hit every 20s burns champions.

Cheap Shot
Deal bonus true damage to enemies with impaired movement or actions.

Morgana Q and W
Arcane Comet
Damaging a champion with an ability hurls a damaging comet at their location.

In teamwork/teamfights your job is to catch enemy adc/apc with your q while sieging. Since q snare is the longest cc in game your team will have window of opportunity to kill that target.

In teamfights your job is to get close as many enemies as you can and press (r) if they focus you just use your zhonya and after your 2nd ulti thick you can q-w one target and get away. Since you ahve high cooldowns after that you gotta retreat and let your team clear the low health ppl. Do not overstay your auto attacks will be useless in late game.