pitfall trap rulings

[Swamp]

For this card from Zendikar:

pitfall trap 2W
Instant --Trap
If exactly one creature is attacking, you may pay W rather than pay Pitfall Trap's mana cost.
Destroy target attacking creature without flying.

Can I cast the ability for reduced cost if the only attacking creature has flying?

[Twanos]

No, you must have a legal target when you announce the spell for it to go to the stack.

[Rocket]

even if you could why would you want to, if theres only one attacking creature and it has flying then there wouldnt be anything to destroy and you wouldve wasted the spell

[Ditto]

I also have a question about pitfall trap rules,

what if the other player declares 2 attackers, and after attackers are declared I bolt one of them so now theres only one attacker only, can I cast it for 1 mana? or maybe not because when attackers were declared there were 2? Whats the ruling?

[Twanos]

The opponent is running discard so your would rather burn the spell than take dmg from Megrim?? lol

[Ditto]

Originally Posted by Ditto

I also have a question about pitfall trap rules,

what if the other player declares 2 attackers, and after attackers are declared I bolt one of them so now theres only one attacker only, can I cast it for 1 mana? or maybe not because when attackers were declared there were 2? Whats the ruling?

Anyone know the answer to my question

[Twanos]

Yes you can cast it for 1. It will check at announcement.

For you to not be able to it would have been worded...

If exactly one creature was declared as an attacker, you may pay W rather than pay Pitfall Trap's mana cost.
Destroy target attacking creature without flying.