Just some thoughts I had about other things that could help differentiate the Realms from each other.
Upgraded resource piles, essentially. Encounter rate would be 1/10th normal resource spawn rate, and each one would give 2-3 times the normal drop amount plus a buff on one of your creatures for the next battle.
Fruit of Life: Found in Life Realm. Gives Essence and Protect to one creature for the next battle.
Ice Diamond: Found in Winter Realm. Gives Crystal and Frozenarmor to one creature for the next battle.
Alchemy Set: Found in Sorcery Realm. Gives Power and Ward to one creature for the next battle.
Cairn: Found in Death Realm. Gives Granite and Berserk to one creature for the next battle.
Devil Nest: Found in Chaos Realm. Gives Brimstone and Splash to one creature for the next battle.
Penitent Scroll: Found in Dungeon Realm. Gives ritual energy and Multistrike to one creature for the next battle.
Hyacinth: Found in Nature Realm. Gives a small amount of each resource and Dodge to one creature for the next battle.
We’re all aware at this point of the problem of resource overabundance; so why not add a randomly-spawned object in the Realms that allows you to sacrifice the variety of resources available for some kind of ulterior benefit?
Whispering Altar: Found in Life Realm. Sacrifice Power to learn ancient secrets and gain Player XP.
Crystalline Font: Found in Winter Realm. Sacrifice a core before the frozen fountain to level up one random gem.
Astronomer: Found in Sorcery Realm. Give him Crystal for his telescope lenses to recieve Star Maps (consumables that reveal the floor plan).
Dollmaker’s Hut: Found in Death Realm. Give her creature remains (consumables) to recieve Power Balance / improved Loot for the next battle.
Torchbearer: Found in Dungeon Realm. Give him Brimstone for his torches to recieve payment in Tokens.
Mossy Obelisk: Found in Nature Realm. Sacrifice Granite to the climbing vines to recieve Creature XP from the flowers that bloom.