Race! In my city

[ivy2112]

I am making a new race parkour , to have a race fort 2 persons in my city underground
I am asking here if i can " duplicate " blocks , the reason i put the " 's is that it shows the block but it also doesnt dupe the block Video of proof :
http://www.youtube.com/watch?v=Zb8iFoVnKGQ&feature=g-all-lik
It's called phantom blocks , it's awesome to make traps for it ,
Is that kinda trap allowed ? ( ofc it's with a water drop so no falling damage )

[hennydeez]

according to the video, it seems like they are shape shifting blocks, so i see no block duplication.
if you're going to make a trap, make sure it's player friendly.

[ivy2112]

As i already said it has a water drop so it's safe