You talk about forging a good bit, but it doesn't get its own section. I'm not sure if it deserves one or not, but I'd in my mind part of choosing a rainbow is getting access to items that you cannot otherwise obtain. The minimum paths you need to forge everything in the game are:
Air 3
Astral 3
Blood 2
Death 1
Earth 2
Fire 2
Nature 2
Water 1
Forge
Earth Boots (+1 Earth)
Forge
Dwarven Hammer (no path increase but significant reduction in item costs)
Forge
Starshine Skullcap (+1 Astral)
Forge
Crystal Coin (+1 Astral)
Forge
Ring of Sorcery (+1 Astral, Blood, Death, Nature)
Forge
Ring of Wizardry (+1 to all paths)
The
Ring of Wizardry gives you Air 4 to make Air boosters. The
Ring of Sorcery and
Ring of Wizardry give you Blood 4 to make Blood boosters. DO NOT equip the
Armor of Twisting Thorns on your pretender because you cannot take it off. The
Ring of Sorcery and
Ring of Wizardry allow you to forge Death boosters with a
Dwarven Hammer. Without them you have to forge the
Skull Staff and
Skullface without a hammer because the
Skull Staff requires both hands. The combination of Fire and Death allow you to forge a
Skull of Fire, and the
Ring of Wizardry gets you to Fire 4 to make the
Flame Helmet. After the
Thistle Mace, you can make the
Moonvine Bracelet and/or the
Armor of Twisting Thorns, plus the
Ring of Sorcery which gets you to Nature 5. The
Water Bracelet and
Ring of Wizardry allow you to forge the
Robe of the Sea.
From here you can forge the
Robe of the Magi by wearing the
Winged Helmet, both rings, and a
Blood Thorn. That gives you access to a huge list of spells and the ability to forge every artifact in the game as far as I know, since no artifacts have a path requirement higher than 6.