I know how to beat horrors (two biters combined) in practice mode. First, unlock the teleporter reward( the 10th reward) then go to practice mode with just horrors and drop the teleporter in one of the corners. Lure the horror into the corner opposite the teleporter then teleport and then if you're lucky it'll send it's disks out then then the horror will turn into a regular gloople and then kill it before it's disks come back.
I'm not sure if this works but right when your tense meter gets filled up by scraping bullets right when it's at the highest point press space to activate the big thingy.
ALMOST THE BEST GAME EVER!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 "Get Off My Lawn"){kind=icon}
 "How to Raise a Dragon"){kind=icon}
 "SHIFT 2"){kind=icon}
 "Shadowreign RPG"){kind=icon}
 "Amorphous+"){kind=icon}
 "Frantic 2"){kind=icon}
 "Bloons Tower Defense 3"){kind=icon}