I was playing around and I got different color auras. But I don't know how to trigger them! I know Cyan blue aura, but I don't know how to trigger it. Can you help by describing all the auras and how to trigger them?  

Yellow is 50 streak
Blue is kill 2 people within 10-20 seconds(?)
Cyan is respawn quickly  

To add on.. Yellow also restore all your lost HP and is triggered by getting a 50 kill stream, blue is by killing 4 people in a row under 10-20 seconds which gives you a speed boost, cyan gives you more hp when healing and its triggered by using healing items, there are also red and green but unsure what those are.  

Red is when you kill ten(might be less, not sure) people in a row with an explosive weapon, and it gives you explosives of some sort.