Throwing a random idea. How about WoW-styled enchantment? You can craft scrolls tiered by default Terraria's progression.
Tier 1: Pre-Skeletron.
Recipes something like mana star + cloth(because we don't have any paper) + gems or whatever.
Possible effects would be a +single stat of uncommon power. Maybe with a ruby, it could allow you to apply "On fire!" with a melee swing. (Flaming swords basics of rpg-genre 101)
Tier 2: Pre-Hardmode
Books, water candles, and gems. Theoretically, you can raid the dungeon and get a few books, and maybe a candle pre-Skeletron, but I'm cool with that. You can find water bolt in the same way after all.
+single stat rare. More potent versions of "On Fire!" and "Frostburn"(basic) for all weapons.
Tier 3: Hardmode
Souls, crystals, ichor/cursed flames and spellbooks. For stat enchantments - gems. Also, this way gems will be useful all the way to the Moon Lord.
+stat rare and a random stat of uncommon quality. Ichor or cursed flames on hit(guess, which one of them everyone is going to use
Crimson ftw.)
Tier 4: Post-Plantera
Lyzhard power cells(doesn't require you to kill a golem), Ectoplasm, spellbooks. Gems for stats.
+stat epic and a random stat of rare quality. Also, the love of my life enchantments aka
Moongoose. Random chances on hit to receive a buff which raises crit chance/"main" stat/movement speed/jump height/velocity etc. "Proccing" +stat enchantments should result in a bigger buff, but be inconsistent.
Tier 5: Pillars
Those four pillar fragments, Martian plating(?). Gems for stats.
+stat legendary and a random epic or two random rares. "Proc chants".
Scrolls target the first item at the upper left(as usual with this kind of mods). Maybe craftable at enchantment table(any table + cloth + mana star?).
Again, your mod makes my imagination go wild with possibilities. If you do like the idea, however, maybe it could also be applied to armor and accessories. This way, the player is less susceptible to rng and more to grind. Dunno about the chaos mobs drops, though. That is, if you ever intended for them to drop enchantment items in the first place, though.
Sounds really cool. But I have no idea what so ever, what this effects could be. Would love to hear more about this topic, if you don't mind sharing some spoilers.
This one is tough. I myself play on Calamity's Revengeance mode(more spawn rate, although, I don't know how much precisely) and use a demon trophy(x1.25 spawn rate). Throw a battle potion in here, and basically, you have a bloodmoon+ everywhere you go. On the other hand, it doesn't increase chaos mobs spawn rates specifically.
Anyway, between the Reduced Grinding's war potion, battle potion, Calamity's spawn rates and Fargo's Mutant Mod's War Banner(x10 spawn rate!) there is more than enough grinding enhancements already on this forum.
Same as with the scrolls sounds cool, but I have no idea what you mean specifically by this.
In regards to what ShuVi said about the topic.
Any way to implement a timer that just turns next mob that spawns after a period of 10 seconds into a chaos mob, and then sync the timer itself between clients and server? And then you can implement "bloodmoon" like effect that reduces this time period. I have no idea how these things work in Terraria and this is quite a choppy way to implement something, but I guess this is better than nothing? Or just really make an event like a bloodmoon that turns everything into chaos mobs, can occur both "natural" and be called upon, and call it a day?
But I'm totally just throwing random workarounds here.
Attached is my random spriting attempt of what enchanting table could look like. RIP diabolic Sigil.
View attachment 179877