Getting hit for 400 + health instantly from assassins env poison then purging it and getting instantly hit for another 400 + health damage because of the lame /switch they have here is way OP and needs to get changed. Assassins essentially get to do 800 + damage to you in less than 2 sec . If you Purge it you should get the hit points back and get immunity to the env poison making purging the poison actually useful rather than detrimental.