Description from original post (created 2012-04-11 19:10):
Gurdy is one of the four mutant bosses that you can face in the caves levels. She is a static boss that remains stationary in the middle of the room. When you enter the boss room, Gurdy is usually there with a few boils and flies of random variety. Every few seconds, her head will come out of the blob on the side that the player is on and vomit a wave of blood towards him; these waves can be quite challenging to avoid. Also, roughly every half a minute, she spawns a fly (usually a Puster) that you will have to take down, as you will have to dodge its shots as well. You will also have to avoid the blobs of blood shots that the boil shoots at the player.It is advised that you try to destroy the boils before you start on Gurdy, but be aware that you will have to be quick shooting Gurdy, because she will randomly spawn another set of boils that will make life a bit hard. Since Gurdy is stationary, she has alot more health than the others to compensate for not being able to move, so it is best that you just persevere on destroying the boils and geting as many shots to Gurdy as possible.
Gurdy is by far one of the hardest bosses in the caves levels (if not the hardest), as she takes so long to kill, all the while having to also destroy the boils and the flies that she spawns. You have to try not to get bored of fighting and lose incentive; just keep at her, she'll die sometime
Info from http://bindingofisaac.wikia.com/wiki/Gurdy
Picture from http://bindingofisaac.wikia.com/wiki/Gurdy