I got the idea of pets, these are types of towers you can have in every level, but are EXPENSIVE.
They level on they’re own, just use them. And if they die then after the level you can use them again.
Here is one of my ideas:
The frog hops to a random spot every round. It uses its long tongue to reach enemys. It can only eat red, blue, green and yellow. It takes 1 damage if it eats no balloons a round because of hunger. And it takes 1 damage if it eat 30 or more balloons a round because of over eating.
Starts with 2 hp.
Bigger tounge: Bigger tounge.
Big mouth: Can eat rainbow balloons.
Spikey teeth: Can eat lead balloons.
More hp: plus 1 hp on upgrade.
Costs: 5,000 monkey money.