Build and Runes
Try not to target him if he has his Defensive Curl on – as he will take much less damage, and he’ll also return some damage back to you.
Try to stand amongst creeps to avoid getting knocked-back by Rammus’s Powerball.
Most Rammus players build heavy armor. This will make him vulnerable to AP damage.
Taking cleanse or buying a Quicksilver Sash will let you immediately cure his taunt.