You know what, Dragon Master Swain could easily be an ultimate skin
Just imagine it, being a true master of dragons he has several 'beatrices' which are interchangable (like how DJ sona can change) and depending on who is sitting on Swain's shoulders, all his abilites have different particles.
I do realise he is unlikely to get it until his VGU (I will be sad if he has a completely different play style such as the sion rework) but still an awesome concept.
Fire dragon: Appearence: His clothes are all red, lava footsteps Q: sends out a fire dragon shooting out flames from its mouth W: Surrounds an area in a min-volcano and when ready, lava spews out and cools down holding all in the area E: Sends a fireball to burn his enemies R: He turns into a fire dragon sending out fire drakes to heal him and damage others
Water Dragon: App: Blue clothes, water splashes when he walks Q: Sends out a water dragon acting like a water cannon W: Creates a pool of water which quickly disappears, leaving behind quicksand, holding all in the area E: Sends out scalding hot water at his opponenet R: Turns into a Water dragon sending out water drakes
Air Drake: App:White clothes, Flies/hovers Q: Beatrice shoots out a tornado breath W: Not sure on this one actually E: Sends out a ball of wind that encricles the enemy, damaging them R: Air Drake
Mountain: A: brown clothes, footsteps leave holes Q: Beatrice sends out a constant stream of stones at fast pace W: rocks form in an area and 'grabs' onto enemies still in it E: He throws a boulder that damages enemies over time as the boulder crumbles R: Turns into mountain drake
Void Dragon: A: Purple clothes, footsteps leaves mini rifts between the void realm and runeterra Q: Beatrice Sends out purple/black ooze from her mouth W: Creates an purple area which suddenly sprouts out void thorns to hold people in place E: Sends out a leech-like creature R: A void dragon (would look badass)
The different drakes were inspired by the in game drakes with the void drake is baron. Changing between forms would be him surrounding himself in an egg before hatching out into his new form. Different taunts depending on the mode he is in. EG. fire drake has different taunts for annie/brand
Again, I realise that this skin probably won't come out till his VGU but looking into what it could become if it was released today is always interesting.