Within the pools of the Endless Swamp, Ooulzoth started to brew new and deadly creatures.

New virus strands and bacteria formed and grew. Tiny parasitic worms and blood sucking leeches infested the waters of the plane and the material swamp it stood in contact with.

The Myxiniloth and Gibbering Horrors formed symbiosis with these, and there bites and slime became even more vile, for the slightest touch would infect any mortal (and lower outsiders).

Because of the high concentrations of infectionous organisms living in the Swamp plane, any creature created by Ooulzoth in it is virtualy immune for any disease or poison.

(3Ap = 4Ap - 1Ap ; create deadly diseases & parasites)
(dunno if this would cost 1ap or 2ap, since it isn't realy a race that's been created)