how to play comet storm with example

[Footprint]

can sum1 explain (with example) how to use comet storm?

[Arix]

Your opponent controls three 4/4 creatures, and you want to kill them all. You need to deal 4 damage to each, so X = 4. Then, since you have two extra targets, you need to kick it twice. So you play with for XRR, paying an extra 2 to kick it twice, and choose all three 4/4s as targets. It resolves and deals 4 damage to each target.