Question about the one invisible green dragon tactic

[jynki]

I was wondering if someone could explain this tactic? (Clinek wrote this in another post):

Round 1. Cast invisibility, then armageddon. Get close to your enemies and defend

Round 2, cast some low level spell on the enemy the wait. Once all of the enemies have used up thier turn, use time back on the dragons, the go use the mana sucking ability of the dragons to get all of your mana back. Repeat round one and 2 until enemy is dead.

Allright, round one works fine for me too. but when i use the mana drain-skill with the green dragon his inivsibility breaks and hes turn is over and hes gonna get slaughtered when all opponents get to move before you can recast invisibility again? or am I missing something?