@Riot @Meddler Your parasite/shapeshifter champion. Here's an idea that might work.

Take a blob and attach bug-esque wings to it, or something akin to what Pix has going on for him. Give it a mouth and perhaps one large eye.

From there, let it latch on to allies with its W, allowing it to Q and E whilst latched onto said ally. For its ult, you could allow it to boost the offensive and defensive stats of whoever it's attached to. Alternatively, allow its W to scale offensive or defensive stats passively for the blob and whoever it's attached to and have its ult latch on to an ally.

Alternatively, W latches on, and the ult forces a carbon-copy of the character to be made that attacks what the copied character attacks, uses the same abilities, and soforth (damage reduced by 25 or 50% or so).

The latch can last for a minute or so, or indefinitely if you really want, but it takes 2.5 seconds to un-latch from a character and you come out with half of your total HP if you end the latch early. If your latched target dies with you latched to him, you also die.

If we want to get really nasty, let it take complete control of an enemy character for 2 seconds or so with its latch being its ultimate (castable on allies or enemies) with a moderate range of 450 or so.