can you rune crimson gem and the vine? im just wondering cause vine is a light object and cost zero points

When placing objects you can have 1 Light object, 1 Heavy object, and 1 Object of any kind (light, heavy or immobile). It does not matter if they are special objects or not.

So, the Crimson Gem is Immobile and Vine is Light. That means if you do decide to use a third objectives it would have to be a heavy.

The only restrictions that Special Objects have is that they are all unique, so you could not use two Vines.