Annie's Molten Shield

I use it for the damage resistance, but its Thornmail effect is almost useless. The timing on it is too short, and anyone who is basic attacking her, even minions, aren't going to get more than one or two hits in, and that's if she didn't stun them first.

Would it be possible, instead, to give her Molten Shield a Sunfire Cape-like effect? It would probably work best combined with her close range kit.