Cassiopeia poison cloud invisible to all of us ( the enemy team) BUG [GAMEPLAY]

Just played a game where all 5 of us on my team could not see the enemy Cass Poison Cloud ability on the ground. Zero animations. died and took lots of damage from invisible spell. Pretty darn game breaking not being able to dodge or have anyway to counter such a strong attack when you cant see it.** Please disable and fix**. Not fun and game breaking dying to nothing.** Happened to all 5 of us at once, so not just a one off thing**