I'm making a poison ivy styled hero at the moment and I can't find any Kryptonite Isotopes to get Krypton-Vine Leggings so it can match with the Plant style chest piece.
====Did it get taken out of the game???====
====Did it get taken out of the game???====
This is something for the DC Universe Online Wiki, but as I'm a former player myself, I'll answer it.
It's still in the game. It just drops in the most annoying location, with a lot of high, yellowish buildings - Downtown and Historic. They're also rarer than the other collections there (expect lots of Daily Planet Passes, street names, pennants and MDP files), and several are slightly under Superboy plaque/Arkham Jokerz-level rare. You're going to have to grind a lot with node scanners. Make a note of where the nodes spawn and check back regularly.
I've spent hours there. Days, even.
Or, save millions and buy them in the broker for way too much.