The Water heroes are cooling off, and are making their enemies do the same, because all Water heroes with skins equipped are getting the Chilled Skin passive during the event. They've also brought along some barrels of fish, because they seem to love fish. You probably don't care much about their fish, but there are other goodies in those fish barrels that you'll enjoy, like tokens, celestial evos, and other loot! Why did they put loot in their barrels of fish? I guess to save space. And this also proves that tokens and evos are waterproof!
But the biggest wave being made in this event is the all-new Community Dungeon Dash event that will be running along with the Water Festival. This is a simple event that lets the community work together to earn lots of extra prizes! Every dungeon run (both manual and quick loots) and PVP raid gets counted towards the community total and your personal total. At the end of the event, we will pay out rewards based on the total number of dungeons run to all players who contributed at least one dungeon run. On top of that, the individual players who did the most dungeon runs will get additional prizes!
One of the prizes for the Community Dungeon Dash is a a brand new type of rune: Community Runes! These give heroes a chance to do an extra basic attack after their normal basic attack. These basic attacks work just like Pignius' Hog Wild ability. They will trigger off of non-Epic attacks, and do not stack with Hog Wild, but can stack with other Community Runes.