I keep encountering odd green portals I can't use? how do I trigger the things? They look like the purple portal aside from swirling green energy in the thing. 

These are a Tundra exclusive thing! They only exist on Tundra islands, which will only be available until the beginning of March.

To use one, you have to have a Portal Energy Cell. There are two ways to get one. First, you can be very lucky and find one on an island! Second, you can craft them, which is harder. 

First, you need Charged Sticks. These can be bought from the State Store, but the cost adds up pretty quickly. Alternately, they can be crafted using Rocs with Lightning Strike (although the materials for crafting are on the expensive side). Once you have Charged Sticks, you can craft Portal Energy Cells using them. (Both recipes can be bought in the State Store, and I believe sometimes you can find them randomly on islands too, during winter.)

At higher levels of the tundra, you can find Hibernating Eggs (which hatch into "wild" Lykos) or even a Pristine Snowflake (activates into an Etelia, which is a cool and unusual pet). For details, see the Main Page (there's currently an announcement about tundra season) and the tundra exploration guide in the Guides forum. 

Oh thanks! it confounded me when I kept seeing the green thing XD