So, that arcade teaser

So far, I think it's pointing to

2 reasons

The electricity before the game over screen? Yes, could be blitzcrank's ult, but it seems constant, more akin to Viktors. The ! icon could just be the centerpoint projecting the field.

Blitz laughing in the background alludes to this as well, since his inventor, albeit uncredited, was as well

Aside from that, I really don't see the angle they're approaching from since he already has a legendary, and doesn't(?) really fit the arcade theme. Just have to wait and see.