[Lucid:]

I've never actually seen somebody go Darius support before. I've heard it's good and I'm sure that pull is great for getting some kills, but he doesn't offer a whole lot else.
Ignite's fine for securing kills in lane but by the time teamfights come around, defensive spells are going to help an ADC a lot more. The carry shouldn't be in range to use exhaust/ignite on the right target.