@Riot, Potential Problem with Ekko's Ult Mechanics (tested on PBE)

Riot may or may not be aware of this mechanic with Ekko. Ekko can back to base and ult himself right back to wherever he was on the rift so long as he buys within 4 seconds of backing. Ekko taking teleport can cause his presence on the map to be outrageously good. Not to mention judging from playtesting from the PBE he has great 3-hit burst. Hypothetically speaking Ekko can TP bot, get out a VERY quick combo (so long as it's within 4 seconds) and then ult straight back to mid/top or which ever lane he will be favored in. These are two scenarios that may not have been thought out from Riot that could cause Ekko to be god-like.

Also consider homeguard boots and cooldown on this champion. His ult can get to about 47 seconds I believe at lvl3 40% CD.

Obviously this is just my opinion and Ekko isn't even released to live yet but I think purely mechanically speaking that mobility/map presence is really powerful.