Biotics: good for only 1 thing
Biotics are people with eezo in their bodies and the ability to manipulate it. Off the top of my head I can think of several ways to kill someone without even touching warps or singularities such as:
- briefly reducing someone's mass while running and watching them catapult away at thousands of km/s
- reducing the mass of the blood in their heart, wreaking havoc with their blood pressure (possibly resulting in a goresplosion)
- increasing the mass of some vital organ so it rips free of their ribcage
- reducing someone else's mass while kicking them (let's mess with the physics engine, YAY!)
- reduced mass baseball+throwing arm=improvised mass accelerator
- increasing the mass of someone's blood and watching as some incredibly painful medical condition related to not getting enough blood to vital organs takes them out
Telekinesis can be achieved by stimulating an artificial gravity well, but it will be imprecise and tend to end in a way similar to katamari damacy if kept up for an extended period.
However the most devastating thing a biotic can possibly do pertains to the weird way mass effect fields interact with temperature.
If you payed attention in science class, you probably know that temperature is based on atoms moving around randomly and banging into each other. This means temperature is a form of kinetic energy. When someone's mass is reduced, the energetic chemical reactions that power them are still producing the same amount of energy, but that same amount of energy is suddenly resulting in their atoms catapulting around at hundreds of km/s. As long as their mass stays lightened or the amount of lightening is reduced gradually, the person in question will be (mostly) fine with some possibility for overheating unless their biological homeostasis freaks out after realizing that their temperature is technically in the low millions of degrees and tries to correct this, resulting in hypothermia. However, like an FTL drive the really scary thing happens if the mass lightening fails suddenly. When that happens, the 'technically' bit of 'their temperature is technically in the low millions of degrees' goes away and they sublimate into hypervelocity plasma almost instantly.
It's that weird interaction with temperature which is the primary reason that FTL is likely to be the only civilian application for eezo besides communications ever. However (as I will detail in the next installment) those comm buoys and relays have quite the potential for horror on their own.