In Yugioh are you able to use forbidden lance on a clear vice dragon with zero atk and if you are able when clear vice attacks does it loose 800 atk after its atk is doubled?

Answer 1

You are able to use Forbidden Lance on Clear Vice Dragon and it'll indeed lose 800 Attack after his Attack is double the Attack of the opponements monster.

Example:

You use Forbidden Lance on Clear Vice Dragon and then attack a Elemental Hero Burstinatrix(1200 Attack Points) with it, then your Clear Vice Dragon's Attack Points get 2400 and he loses 800 Attack Points because of Forbidden Lance. So he'll end up with 1600 Attack Points.