Regarding the issue of ranking:
I suggest to have two separate scores.
One is the main score used to rank players. The other is the tiebreaker score. If 2 or more players tie for the main score, then the tiebreaker score will be referred for tiebreak.
Also the tiebreaker score can be different every Colliseum. It can be used to change the play behaviour of players too.
If win, +1 per round played. This will make competetive players play more rounds instead of going for an immediate KO.
If win, and if player's life point is less the 5, +1. When decks that are even in power level meet, the more skillful player will win, but usually with a small margin of life left.
If win, and if player's hand's total star is equal or less than opponent's hand's total star, +1. Reward skillfull player.
There are many more parameters that can be used.
Just an opinion.
So,hmmmm,coliseum ends to be racist. Firstly 8/10 formats discriminate against ordinary players. Secondly 7/10 coliseum time is for particular community. Thirdly,on top of all, it puts playets who played last with same score at better rank. So even at unfortunate times I play with heavy eyes at midnight,there is no saying I will end in top50 because of scoring system .
on top of all,no one intends to accept or apologise mistake so this post goes to trash