>Biohazard champions create a patch of poison on a semi-random, unmanned tile on combat start that deals % max health damage each second to enemies standing on it and prevents healing.
>0/2: Two fields (four total)
0/3: Two fields (six total)
0/4: Three fields (twelve total)
Note: Semi-random means the spawn chance increases closer to the champion spawning them based on their attack range.
Alternative effect: The poison patch is consumed the moment an enemy steps on it to poison them for % max health damage over time. Might reduce visual clutter.
**Twitch** Ranger/Biohazard 1 Gold
Ultimate: Twitch gains attack damage and his basic attacks pierce two tiles behind his target for a few seconds.
**Cassiopeia** Imperial/Biohazard 2 Gold
Ulitmate: Cassiopeia slithers up to her target, deals damage to enemies in a cone in front of her, and stuns those looking at her.
**Singed** Brawler/Biohazard 3 Gold
Ultimate: Singed flips an enemy into the nearest available space or poison patch behind him, dealing damage and briefly stunning them.
**Teemo** Yordle/Biohazard 4 Gold
Ultimate: Teemo throws a poisonous mushroom at the nearest enemy that explodes after a brief delay to deal magic damage over time to them and all enemies in a circle around them (up to 7 targets total). Then, he very briefly goes invisible.
So design-wise, three out of the four Biohazard champions would have ultimates that cause enemy champions to reposition and possibly walk into poison tiles. Cassio moves, causing any melee champions attacking her to follow after her, Singed throws people into his targets, Teemo goes invisible to break engagement on him which causes melee champions who were attacking him to move to find a new target.
This causes lots of movement on the map, which can mess with enemy positioning and which makes your own positioning a key factor of a Biohazard Build (e.g. leaving a field open in the middle of your comp so an enemy Assassin will jump right into a poison patch, placing your units so that enemy units will have to walk up through poison patches, etc.)