Sounds like you're off to a good start. I'm not especially in love with carapace myself; I kind of view poison as a weak version of creature control. You'll take a lot of damage from say Graviton and Miracle waiting for poisoned creatures to die. Consider a different shield with maybe otys for control. Adding quints would protect your otys, your damage creature(s), and your butterflied creatures if you choose to go that way.
Aflatoxin works well with other poison cards like bone wall, bone yard, and vultures, as well as flood. Food for thought.
While I'm not against a PA, you may not need one to protect your pulvy as much as you think because FGs with bonds don't have perm control.