Mastemon, with a strange build
Okay, so this is gonna look really weird. This deck plays like a Mastemon turbo deck, as it focuses heavily on Mirei's ability to play level 5s for free.
In Bt13 a new Geogreymon was released that allows you to play tamers from security for free. That's good. What's not good is that I believe the yellow rookies and especially yellow eggs that we currently have absolutely suck, so I did an insane deck building choice and decided to use purple eggs while using yellow rookies that digivolve from purple eggs. This allows me to use both Geogreymon and a good purple egg, as well as Psychemon floodgates to stop Royal Knights.
Because of this quirk, Nyaromon is actually the best egg of choice for the deck now, as most of my rookies are Yellow, meaning I can get the draw 1 trash 1 without it having to die in security (my record is a Geogreymon that swung 3 times! That's 2 extra cards drawn than if I was using Demimeramon)
The other strange choice is Metalgarurumon Ace. I believe in its place in the deck, as this deck plays more turbo / combo rather than stall or control. The main level 5 of choice to revive from Mastemon is Lucemon Chaos mode, which Metalgarurumon can digivolve off of during the opponent's turn! The card also is a 6 cost level 6, which makes it a genuinely decent choice just to drop when Mastemon bricks (which happens more than you'd like) and its removal is nothing to scoff at. Being able to be dropped for a cost of 6 allows it to instantly go into Ordinemon if you have the end-of turn DNA on the other card!
My matchups on the day were Ravemon (I killed all of their tamers with Lucemon and Zwart Defeat), Bloom Lord (Ordinemon popped their field and recovered me 4 security), and Beelzemon (they would try and kill the Gatomon every turn but the one time they couldn't I was able to run away with the game)
