X-Men 2: Clone Wars/The Savage Land

The first stage is the Savage Land exterior, where you must manoeuvre through the trees and swamps. The second stage is the Savage Land interior. The third stage is the Flooding Fortress, and the fourth stage is the Flooding Fortress upper floors. The boss of the level is Brainchild.

Brainchild
This multi-part boss fight doesn't take too long. When the fight starts, all that's on the screen is a simple floating device that drops rockets that slowly shoot toward you. When you destroy it, Brain Child emerges as just a simple enemy firing a gun. After some damage he transforms into the basic enemy from the previous stage, then the basic enemy from the proceeding stage, then a bizarre vehicle that shoots projectiles, charges at you, extends its neck out a bit like a club horizontally then diagonally, charges again, the teleports to the ceiling, where it fires rockets down vertically at you. Psylocke is the optimal character. When the initial vehicle is destroyed several pieces of health emerge and so she she easy to keep at peak health. Brainchild and his subsequent two transformations are destroyed by one peak psychic knife and the vehicle beast transformation can be destroyed (via psychic knife) before if finished the head thrust attack.