Mission 23

The bluetonium is right below your feet. You can use the Portal Generator to get to it or bring it to you or you can use Energy Manipulation in Blue mode to move it along the edges and towards the top of your cage.

The top of your cage is a barrier that you can destroy, but when you do a large number of fleas will drop down.

Your priority is to destroy the sentinels before they get a lucky shot on you. Try to time your approach towards them or wait until Blue mode and use Bullet Jumper. Throwing grenades or turrets into their holes is a fairly safe way of dealing with them.

At the very top of the level, past the platform swarm, is an area with several spawners and a trap generator.

Mobility upgrades are very helpful on this level.