I would love a transformation powerup. Here's how it works:
Upon using the powerup, you change into a playertype (specified in an RTB pref) for a certain amount of time (again, specified in an RTB pref). This would be great for DMs and TDMs, e.g in a futuristic TDM a player can become a mech for, say, 30 seconds. As well as this, make a toggleable option to load a certain inventory for the player upon transforming which would revert back to the previous inventory once the powerup has run its course.
Just a suggestion :>