Apokarimon Creepy Mode can come out of nowhere and win games.
Use him after you've seen whether or not your opponent will digivolve. If you're at 700 points or more he can flat out win you the game.His ability to void all power options can come in handy clearing out control nasty stuff that stays on the power port. If you're worried about your opponent defeating him next duel, arrange it so your deck runs out after the first fight with him.
Ways to counteract it:
Beezlemon will kick his butt, as will any champion level digimon with a red attack higher than 420.
Apokarimon Creepy Mode will probably come down, win one duel, and score you 300 points if you set it up right. After that, since you can't enhance him with power options, your opponent will probably beat him with a champion unless your deck runs out during regroup. This, unfortunately, will tend to score them a good amount of points usually as well.
Apokarimon Creepy Mode is a game ender if you use him right. For that I give him 10/10.