u/arsa_id

I'm in the early stages of playtesting. My game is a deck-builder for 2 players where each player try to achieve victory the quickest from 3 shared victory tracks. Each victory track is shared as such increasing your position decreases the opponent. The game has 3 main types of cards each corresponding to each track but also to some mechanics. Like Deck A for Victory Track A usually contains Deck Manipulation effects (Draw, Discard, etc.). Deck B for VIctory track B usually contains Sabotage effects. Same goes for Deck C and anotther set of mechanics. Each deck also has cards with like +2 Track A -1 Track B. The buying system is similar to Dune Imperium where cards you don't play in your turn have a reveal value.

After 3 playtests with my partner and a friend we found that it got monotone quick, as when our decks were settled it just became who can "puzzle" it out better or drew better.

Looking for advice as to what i can add or improve the core game loop?

Currently on my research step for my boardgame, I'm thinking of breaking down the mechanics first. I'm looking for competitive games with semi-cooperative elements, where there could be ways to score points that can only be gained through cooperation.
Very simple example:
Each player can kill 1 enemy for 1 point.
There is a boss that will be easier/can only be killed by cooperating worth 10 points.
I heard that the math to be balance this out would be a little tricky, so I'm looking for any games that might have implemented this well.

Some games I had in mind are Arcadia/Starcadia Quest, The Great Wall, or Pax Pamir.