Tarokka effect for a given die roll and critical success/miss. Is this balanced?


I’m now setting up my first session as DM. I don’t have the whole story yet, but I have a very simple first session that will introduce 3 players to the game (they are 4 in total).

I’m thinking of a few things to spice things up, based on their die rolls.

  • natural 20: critical success, the player gains advantage on its next attack
  • natural 1 : critical miss, the player misses and gains disadvantage on its next attack
  • natural 13: get a random effect from the tarokka deck

I may swap the 20 and 1 rolls by a player (or me) drawing a card from the luck deck, but not sure.

Does this sound like a good approach, or am I risking losing balance of the game?