The rod would be interesting and I nice nod to norse mythos. How exactly would the rainbow bridge look? Is it more like a rainbow stair?probably a 3 wide bridge made of alternating colors of a semi-transparent block.
So I see three options for implementing the Rod of the Bifrist:
1. The rod comes in dungeons, easiest to implement but makes getting to the Frist completely luck.i went into more detail when i first suggested this, i suggested it dropping from a frost giant that spawns in a special cave/den/dungeon in an ice biome. although perhaps some kind of tracker would be good to implement. perhaps making it so that snow golums will move towards it when they're in an ice biome?
2. If we wanted a mob to access to the Frist, I think adding a whole new one just to get their is a bit too much. How about Ice Trolls (or Yetis, I prefer that name) that rarely spawn in the Overworld cold biomes? When defeated the Overworld Trolls drop the rod.
that could be interesting, but if this thing is going to be as hard as i think it is, the player needs a warning, we don't want some new player in iron armor stumbling across a troll, going to the biome completely by accident, and then getting dominated by the first hostile mob they see. that's why partly why i suggested a boss, it's not something you'd just stumble on, and making it difficult would be a good warning.
3. Or we could move the ice castles to the Overworld and have the Baron serve as a miniboss guarding the entrance. I imagine the baron looking somewhat like the ice king from adventure time, with the villager model.
ok, as the creator of the ice castle, i stand firm that it should spawn in the frist. But i'm all for an adventure time reference.
Side note, in Norse Mythology, Midgaurd(earth) was created from the flesh of Ymir, the first and largest of the frost Giants, so we make it so that instead of dying, the Jotun could turn to stone, and could then be resurrected, possibly with materials from either the end or frist. while making it rezzurectable with items not from the frist i admit is a bit odd, i feel it would do well to A. make the rod renewable, and B. allow players who didn't get there first to go to the frist.