Also, the ad being random item or skill point is kind of... bs.
Successful ad strategies are what other games do often. Offer to increase skill point gain by watching an ad after the player has lost. At the beginning of a game start the player with 2 of each item. At the beginning of a game, let them watch an ad to start with 2 more of each item .
Do that and people will be encouraged to watch an ad at the start and end of every game.
Right now, with benefits from ads being RNG, the user needs to spam ads to get back to where they started on first install! and at some point the ad network is not going to allow back to back to back ads, and even if the ad network allows it, the player is not going to watch ads repeatedly when they don't know what they will get.