when my opponent cast a spell and i use a split second card, do i fizzle my opponent spell??? like i countered

Question

e.g. my opponent cast a lightning bolt and then targeted my 2/2 creature, then i use celestial crusader ("flash", "split second" "other white creatures get +1/+1"). to boost my 2/2 white creature, and by using flash & split second to stop his lightning bolt. do i fizzle his lightning bolt??? tnx a lot guys....

Answer 1

no, split second simply means that he can't react to your casting, it has nothing to do with spells he has already cast.

what happens here is he casts lightning bolt, you then have the option to respond. you cast celestial crusader, because it is split second, he doesn't have the option to respond. It comes into play your white 2/2 into a 3/3.

you now have the option to cast another instant or spell with flash before you allow the lightning bolt to resolve, but the only way to make it fizzle is to sacrifice the white 2/2, cast a counterspell, give your creature protection from red, or make your creature untargetable.

unless you can do one of these, his lightning bolt resolves, dealing 3 points of damage to your creature (which kills it).

Answer 2

Nope. Your opponent simply can't respond with spells or abilities. Morph and mana abilities is the only things you can do in response to Split Second. Your creature would ultimately die anyway. Lightning Bolt does 3 damage so your creature would become a 3/3 and then get zapped by Lightning Bolt.