I summon thee boards people for i need your help

So i saw a few people now who if they have the homeguards buff from fountain have a rainbow behind them. How do i get that? Noone in game answered my question :(

Only one player said something about an Icon? I'm really curious cuz i want a rainbow coming out of my champions ass too.

Sorry if it's the wrong boards section btw didn't know where to put that exactly.

But it affects my gameplay experience negatively not having that.