If i may...
the idea was nice idea, but it would require files that have those key OP/powercreep/rare cards that can stand alone.
Pretty difficult considering that most players have no access to suck cards.
OP dilate... bam! instant meta file.
Bringer... boom! instant counter to a possible win condition.
Belus... pew! shutdown possible rushes.
only thing i can think of that can fit in this tourney available early is zuga from the lawt starter.
Which brings me back to my suggestion to maybe let 1 set in so that there is at least some wiggle room to build around (changing my suggestion to 1 set of NON CHARACTER since 3 characters might just power through files). think pucera SS on an elite fencer which could work against speedy files with no def breaking abilities. or maybe even 3 copies of squid which effectively makes a file that supports those precious 3 copies. or legendary unicorn as a meat tank while you try some shenanigans in the back. or three undeads so that you can field 2 units at least before it leaves. or 3 copies of alruane and the file revolves around buffing it/them. 3 gorillas, nuff said.
just putting that out there again, in case you'd like some feedback.