Here's my tower idea: (all prices are in medium)

Looks like a dart monkey wearing a yellow cape. One of his hands hold a ball of yellow electricity. It shoots yellow balls of electricity out its hands. The range is the same as a boomerang thrower. Attack speed 29 frames (same as dart monkey. It's popping power is 3. Price is 650 (medium)

Path 1:
500$ Stronger Electricity: The electro-monkey has gained the power to shoot greater-intensity bolts Popping power is now 5. Appearance changes: Shoots more beam-like blasts.

650$ Shocking Effect: He/she now shoots blue lightning. Slows down a little and pops 1 layer every 2 seconds for 4 seconds. Appearence Changes: Now shoots blue electricity instead of yellow.

1250$ Look! 2 Hands!: He has become a living conduit of electricity; now he shoots electricity out of 2 hands. Appearence Changes: Holds blue electricity in both hands, not just one.

$2500: Super lightning: Super lightning pops 25 bloons.

7500$ Electro bombs: The electro monkey has fused his electricity with bombs! Now when the electricity hits a bloon, it explodes and hurts all of the bloons around it. A bloon that is directly hit get 5 layers popped, the bloons that get hit from the explosion lose 2 layers. The explosion can pop up to 75 bloons. Appearence Changes: Inside of the electricity there is a bomb that looks like the bombs from a 0-0 bomb tower. Name is now Electro bomberNuclear Electro Bombswell nuclear energy gives 20x damage than normal damage

Path 2:

450$ Night Vision Goggles:His trainer gave him night vision goggles he canow can pop camo and has bigger range. Appearance changes: The monkey is now wearing small binoculars.

550$ Faster Shooting: Has practices his electricity so much he now shoots faster! Now shoots at 25 frames and can pop lead bloons. Appearence changes: None

1000$ Super Fast Shot: He has trained himself so hard he now shoots twice as fast Appearence Changes: None

2500$ Lightning Shot: lightning shoot out of his handsand the lighnings faster and more painful to bloons5000$

Lightning Storm: He calls Zeus/Thor/Jupiter/whatever lightning god he believes in to shock all bloons on the screen for 10 seconds. Cooldown: 90 seconds. Apperance Changes: Now has a yellow cape that has a lighting bolt on it

Path 3:

$500: Power attack:

The tower stops bloons for 1/2 a second after hits (40% chance)

$900: Thundering Echo

Thunderclap knocks back bloons (40% chance, (60% chance for Power Attack)

$1700: Power pack

Bloons take 2 damage instead of one (60% chance for thundering echo, 80% for power attack)

$4200: Superspeed

Attacks 3x as fast, 80% for thunder, certain for power attack.

$6000: Shocktrooper

Any bloons in a small radius of the tower are popped no matter what.

Ultima: Inner Storm: $14000, gives 5/5/5 upgrades. Thomas Quang Bui