Blighter

"Let our polluting powers combine!"
"Super Radiation!"
"Deforestation!"
"Smog!"
"Toxics!"
"Hate!"
"By your polluting powers combined, I am Captain Pollution! Ha! Ha! Ha! Ha! Ha! Ha!"

– Captain Planet, Mission to Save Earth Part I

A Blighter is to a Druid what a Blackguard is to a Paladin. Turning the whole “Revere Nature” thing on its head, Blighter seeks to actively destroy nature nature for its own sake rather than for civilization or whatnot. Yes, it’s an entire (Prestige/Variant) Class dedicated to being a Captain Planet villain!

In 3rd Edition Dungeons and Dragons, Blighter is a Prestige Class from Complete Divine and notorious for being one of, if not the, worst in the system. Qualifying requires the user be a 5th level ex-Druid, plus any method of gaining an extra point of BAB (Yes, it is a non-martial class with a meaningful BAB requirement). While Blackguard gained effective levels for all ex-Paladin levels its user had, for a Blighter these five/six levels do absolutely nothing racial HD doesn’t do. What does a Blighter get for this? Spellcasting from the unique Blighter spell list, which is just a gimped Druid list when Druid was already the worst core caster, a variant wildshape, which is behind the wildshape you’d have if you remained a Druid, a crappy blast (Su), and not needing to eat or drink (which is outdone by a cheap magic item). Blighter spellcasting is technically accelerated, but the six dead levels needed to enter mean you’ll only break even in terms of spell levels at level 12 and don’t come ahead till level 14. Perhaps the most pathetic part of the class is that Blighters need to destroy nature to prepare their spells, so if they actually accomplish their goal, they lose all their power! The class is so bad, considered one of if not the worst in the game, that most fans of Red Hand of Doom strongly recommend either a total rebuild of the Blighter side-villain, or rewriting him to be cursed to his current state since he hardly lives up to the supposed instant death he’s described as (especially so if the PCs remember the staff of healing they got early on in the module and what Heal does to undead).

Pathfinder's Advanced Player’s Guide introduces "Blight Druid" as a Druid archetype. This archetype covers, rather than cover the anti-nature for its own sake crazies that Blighter did, is for Druids that embrace natural decay ("ENTROPY HAS UNMADE THEM"). This version is actually pretty fine, mostly because, aside from the Druid archetype standard (that is likely why you’re taking the class) of requiring you pick from a different list of domains, it only changes secondary features with decent trades.