You need to grind a lot with this game by keep dying to gain better card. Otherwise it's impossible to beat the last boss, unless you can tank 1000 dmg every turn or kill him in 1-2 turn (800hp). Not really P2W, but yes the game is not free, there's in game currency & ads, altar and card pack to buy. The point is either you pay or invest your time heavily on this game which seems like the dev stop developing