SRP&Wiz Core is the glue mod I keep the ugly bits in. It started as a private companion to my own modpack, and it is published here because the crashes it fixes are not specific to my pack — if you run a big 1.12.2 kitchen-sink with threaded entity ticking, OpenTerrainGenerator, FutureMC, Ice & Fire or Chocolate Quest Repoured, you have probably hit at least one of them.

Every feature is independently config-gated in config/srpwizcore.cfg, and the config explains each option in plain language. Two rules about the defaults:

Crash and corruption guards ship ON. A guard that ships off never fires when it is needed, and does nothing when it is not.
Anything that changes gameplay, worldgen or saved data ships OFF. The spawn engine, the CQR integration, the waystones and the Ice & Fire controls all start inert, and several of them ship with example values taken from my own pack. Read them before switching them on.

It has no dependency on my content mod. Nothing here requires Scape and Run: Parasites either, despite the name.

Crash and save-corruption guards

Threaded entity ticking

If you run EntityThreading or anything like it, entities tick on worker threads — and several pieces of Minecraft were never built for that. Four separate guards:

Entity tracking. Minecraft's tracking list is not safe to touch from two threads, and when it breaks the server dies with Exception in server tick loop.
Sounds. Entities near you can tick on a worker thread and play sounds from there, corrupting the list of playing sounds and crashing the client. Those sounds are replayed a moment later on the main thread instead.
World save data. Per-world data (map markers, structure data, mod save data) lives in a list that is not safe to write from two threads. If a mod registers data from a worker thread while the game saves, the list can end up with a hole — and everything after that hole never reaches the disk. You lose data with no error message. There is a second, independent option that skips such a hole while saving so at least the rest gets written, and a diagnostic that logs which mod is registering data off-thread.
Chunk generation. The one that fixes the cause rather than the symptoms. When a worker-ticked entity reaches into terrain that does not exist yet — an arrow flying past the edge of the generated world, a mob looking for a path — the game starts generating a chunk from the wrong thread, which is what corrupts biome data and the world save in the first place. With the guard on, such a request gets air instead of new terrain. The cost is cosmetic: an arrow flies on through, a mob finds no path out there. You can also run it in report-only mode first, to find out whether anything on your setup is even doing this.

Terrain generation

OpenTerrainGenerator. In OTG dimensions whose biomes are all remapped to something else, OTG can fail to work out which biome a spot belongs to; nether fortress and mineshaft generation do not expect that and crash the server outright. The guard places no structure there instead of crashing.
Chunk generation memory. Terrain generation borrows scratch memory from one shared pool. When two threads generate at once, one recycles memory the other is still using and you get impossible biome values and a crash. Every thread gets its own pool instead.
FutureMC bamboo. Bamboo placed while the surrounding chunk is still being built can try to grow into a block that is not there yet and take chunk generation down with it. The one stalk is skipped instead. This is what makes it safe to leave bamboo enabled.

Performance guards for other mods

Doomlike Dungeons — a dungeon that fails to lay itself out throws an error for every chunk it would have covered, hundreds in seconds. The failed plan is skipped quietly instead. No dungeon is added or removed; the mod could not build that one either way.
Chocolate Quest Repoured — asking CQR for the nearest structure of a type that is switched off in an OTG dimension makes it search outward to its limit before giving up, which can cost minutes of world-generation time for an answer that was never in doubt. It now answers "nothing nearby" straight away.
Defiled Lands — an adjustable throttle on how fast corruption spreads block to block. The mod has no setting for this, and in a corrupted area the spreading is one of the more expensive things running. 100 is untouched behaviour, 50 is half speed and half the cost. (Off by default — it changes the pace of the game.)
Raids-Backport — as shipped, every dimension writes raid data to the same slot, so they overwrite each other every tick and the game hits the disk on every world tick looking for it. (Off by default — it changes saved data.)

Per-dimension Ice & Fire worldgen

Ice & Fire has global on/off switches for its structures and ores, which becomes a problem the moment you add dimensions: dragon roosts either generate everywhere or nowhere.

This gives you a list per structure — dragon dens, roosts and skeletons, mausoleums, gorgon temples, cyclops caves, wandering cyclopes, myrmex colonies, pixie villages, siren islands, hydra caves, snow villages, and the copper, silver, amethyst, ruby and sapphire ore passes — with one line per dimension: <dimension>=<on/off>[:<chance>]. Chances use Ice & Fire's own "1 in N" meaning and are portable straight from iceandfire.cfg.

Every list ships empty, and a dimension you do not list keeps Ice & Fire's own behaviour, so an untouched config is indistinguishable from not having this installed.

It also fixes a real cross-dimension bug: Ice & Fire tracks "where the last structure was placed" in fields shared by all dimensions, so a roost generated in one dimension eats another dimension's minimum-distance budget and silently suppresses generation there.

Spawn engine

For heavily modded dimensions where the vanilla mob cap stops working and hundreds of hostiles pile up. Rather than trying to repair the vanilla check, the engine runs its own before it:

Population budgets per dimension and per creature type.
Per-mod and per-mob budgets, applied to the spawn candidate list — the game never even constructs what is over budget.
A refill rate limit. A budget limits how many mobs there can be; this limits how fast they come back. Without it, killing a dozen mobs frees a dozen slots that the very next spawn pass refills, and an area you just cleared is full again seconds later.
Diagnostics that show live counts against both my budgets and Minecraft's own cap, so you can measure before you configure.

Off by default, and the shipped values are examples from my pack (dimension 150, its mod list, its numbers). Set the dimension list and the budgets for your own world before switching it on.

CQR × Spartan Weaponry

With Chocolate Quest Repoured and Spartan Weaponry both installed, dungeon mobs stop fighting with plain vanilla gear:

Gear swap — vanilla swords, axes and bows become Spartan weapons of the same material tier, drawn from a list that suits the mob, with optional exotic materials, off-hand handling and a two-handed shield-loss rule. Bosses and CQR's own custom weapons are never touched.
Working crossbows — Spartan's crossbow becomes something CQR's ranged AI understands, so mobs actually fire bolts with it.
Reach-aware melee — mobs carrying pikes, halberds and lances use that reach instead of walking right up to you, and can hold their distance while they poke.
Staff casters — CQR's staff mobs get an Electroblob's Wizardry wand with spells bound to it, and CQR's own casting AI takes over.
Boss-room chest lock with an optional bonus-book roll when the boss dies.
Siege digging (experimental) — a mob that cannot reach you slowly breaks blocks you placed, so walling yourself into a dungeon room stops being a way to win. It can only touch blocks that were not part of the original dungeon.
Attacker cap (experimental) — limit how many mobs go after the same player at once.

All of it off by default; every piece toggles separately.

Dormant Waystones

Rare surface structures that carry you to another dimension and back, one paired waystone at a time. Holding the configured key item shows a particle trail toward the nearest one and its coordinates once you are close. Travel is a channel you can be interrupted out of by taking damage, and the landing spot is found by a bounded safe-column scan so you do not end up inside a cave roof.

Off by default. The key item, both dimensions, the rarity and the scan bounds are all configurable — the shipped defaults are from my pack.

Compatibility

Minecraft 1.12.2, Forge. Needs MixinBooter, or run on Cleanroom.
Everything is detected at runtime. Optional targets: OpenTerrainGenerator (tested against v9.7), FutureMC, Ice & Fire (2.2.9), Chocolate Quest Repoured, Spartan Weaponry, Electroblob's Wizardry, Doomlike Dungeons, Raids-Backport, Defiled Lands, EntityThreading, Enigmatic Legacy.
Works standalone. Optional companions of mine: Insane Tweaks SRP&Wizardry (content) and SRP&Wiz mixins (Scape and Run: Parasites fixes).

Credits

CleanroomMC — modern mixin support on 1.12.2.
PG85 and the OTG team, Alexthe666 (Ice & Fire), the FutureMC authors, Team CQR, ObliviousSpartan (Spartan Weaponry) and JaredBGreat (Doomlike Dungeons), whose code these guards and integrations wrap.

Source: https://github.com/pegek/Insane-Tweaks-SRP-Wizardry

SRP&Wiz core