Help, my games don't last long enough

So I am trying to make a TCG.

This TCG is for a LARP I am going to. It's cool to have games to play in a tavern when it rains outside. Plus it makes a cool collectible item to find and trade in game.

So here's a quick description on how the game works:

- This is a 1v1 game

- Each player has 2 champions. Each champion has at least 4 abilities that exist in the game, but you must only chose 2 of those abilities per champion for your deck.

- You can win in 2 different ways: you can either kill the other player's champions, or reduce the player's Influence to 0, symbolizing that the player has lost control of their champions

- You also have a deck of at least 4 Divine Intervention cards. Each turn you roll a d4, if you hit 4, you get to play the Divine Intervention Card that is on the top of your deck. Theses cards can do things like deal damage to everyone, heal your champions, swap the 2 players' Influence, etc.

- So your deck is simply 2 champions, 2 abilities per champion, and at least 4 Divine Intervention.

Here's how a game goes:

- A player is chosen at random starts

- They roll the d4, if they get a 4, they get to play the first Divine Intervention card on top of their deck (it must be a random deck)

- Champions can have passive or active abilities, during your turn you can play one active ability per champion. These abilities can range from dealing damage to an opponent's champion to reducing the opponent's Influence, etc. So you play one active ability per champion

- This is the end of player 1's turn

- Player 2 rolls the d4, plays a Divine Intervention card if they get a 4

- Player 2 plays one active ability per champion

- It's back to player 1

- The game ends when a player kills both enemy champions or reduces the enemy's Influence to 0

So here's my problem: It feels to me like the games don't last long enough. You can usually kill the other player's 2 champions within 2 or 3 turns, which makes it almost impossible to play decks that rely on OTK-style strategies.

Another problem is that interesting combos usually rely on one champion dealing damage or setting up a OTK and another champion protecting the first one until that happens. This kind of strategy is quite efficient and feels like the game has already been played out before starting. When you see your opponents cards, you already know that you can't do anything against their combo.

Although this could be fixed by adding more randomness and varieties of mechanics to reduce the feeling of things being played out in advance, I have a very practical problem which is that I want to laser engrave each card, so I must keep the design simple enough to not require huge decks.

In general, how do you fix a TCG that doesn't last long enough? Does that mean that my cards are too OP? And how do I add more game complexity with the same amount of cards?

I am sorry if this post sounds confused a bit. It's my first time designing a TCG and I really cannot find any good resource about it. Everything is either "choose a cool design for your cards" or high level stuff like "the player must clearly understand the goal of the game" but nothing like "how to balance your game"