User blog comment:KaiserLos24/Hold on to your buffs - Riot's new teaser trailer/@comment-3974211-20150528000024

My prediction:
 * This is the next champion.
 * The champion consists of two characters - a master and his pet. (Plural pronouns).
 * The pet is monstrous and huge. (Hence the ground is trembling).
 * The champion is a jungler, or excels at skirmishes in the jungle. Or maybe even take control of neutral monsters (a beast master, of sorts) - "Protect your buffs."

(The guy who leaked Ekko's name, appearance, weapon and ultimate also leaked that the champion after him has a monstrous pet that gets bigger with ranks in R.)

I would love for it to be Nunu / Willump, though. Riot stated a while ago they'd actually finished Nunu's model - and he definitely suits ground-trembling and buff-stealing as much as any new champion.