My idea comes from the syfy channel... If our magnetic axis changes we could have another iceage... So my idea is a magnetic realignment arifact.. takes an icy makes it a Terra. Maybe a +1 or2 to one or more of the production output.. no size change but some permanent bonuses Togo with your new update...
Thought about how to gain it.. buy it with green badges.. say 10..?

An Icy world is a world covered in ice. This means that if it was melted it would become an oceanic, not a Terra. But this should be harder to get than 10 green badges. Make this accessible through a mission chain.

I like planet transformations in general, but an Icy->Terra would be too... overpowered isn't quite the right word... Maxed out Icy -> 16x(17x) Terra -> 18x(19x) Gaia -> 33x(34x) Rift. I don't think a 3 step transformation should be introduced.

don't forget to add 5 to the arti (and a possible 6 to the research) for enumeration crystals and kronyn cubes used before the first transform