I reached Omothol a couple days ago but I can't seem to stay there for more than a few minutes without crashing. I crashed 4 times in a row, in single player and multiplayer, in survival and in creative. This one is when I was in creative trying to figure out what was going on, but I have multiple crash reports from other game modes if you need them.

Description: Ticking entity

java.lang.NullPointerException: Ticking entity
at com.shinoow.abyssalcraft.common.entity.EntityRemnant.func_70636_d(EntityRemnant.java:206)
at net.minecraft.entity.EntityLivingBase.func_70071_h_(EntityLivingBase.java:1611)
at net.minecraft.entity.EntityLiving.func_70071_h_(EntityLiving.java:206)
at net.minecraft.entity.monster.EntityMob.func_70071_h_(SourceFile:30)
at net.minecraft.world.World.func_72866_a(World.java:2070)
at net.minecraft.world.World.func_72870_g(World.java:2034)
at net.minecraft.world.World.func_72939_s(World.java:1887)
at net.minecraft.client.Minecraft.func_71407_l(Minecraft.java:2006)
at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:973)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:898)
at net.minecraft.client.main.Main.main(SourceFile:148)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

A detailed walkthrough of the error, its code path and all known details is as follows:

-- Head --
Stacktrace:
at com.shinoow.abyssalcraft.common.entity.EntityRemnant.func_70636_d(EntityRemnant.java:206)
at net.minecraft.entity.EntityLivingBase.func_70071_h_(EntityLivingBase.java:1611)
at net.minecraft.entity.EntityLiving.func_70071_h_(EntityLiving.java:206)
at net.minecraft.entity.monster.EntityMob.func_70071_h_(SourceFile:30)
at net.minecraft.world.World.func_72866_a(World.java:2070)
at net.minecraft.world.World.func_72870_g(World.java:2034)

-- Entity being ticked --
Details:
Entity Type: abyssalcraft.remnant (com.shinoow.abyssalcraft.common.entity.EntityRemnant)
Entity ID: 1630
Entity Name: Remnant
Entity's Exact location: 266.50, 33.00, 121.50
Entity's Block location: World: (266,33,121), Chunk: (at 10,2,9 in 16,7; contains blocks 256,0,112 to 271,255,127), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Entity's Momentum: 0.00, -0.08, 0.00
Stacktrace:
at net.minecraft.world.World.func_72939_s(World.java:1887)

-- Affected level --
Details:
Level name: MpServer
All players: 1 total
Chunk stats: MultiplayerChunkCache: 121, 130
Level seed: 0
Level generator: ID 00 - default, ver 1. Features enabled: false
Level generator options:
Level spawn location: World: (124,64,256), Chunk: (at 12,4,0 in 7,16; contains blocks 112,0,256 to 127,255,271), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Level time: 5611626 game time, 1286083 day time
Level dimension: 0
Level storage version: 0x00000 - Unknown?
Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: false
Forced entities: 32 total; [EntityClientPlayerMP[''/379, l='MpServer', x=326.75, y=66.87, z=38.80], EntityRemnant['Remnant'/2818, l='MpServer', x=316.50, y=37.00, z=103.50], EntityRemnant['Remnant'/2053, l='MpServer', x=328.41, y=66.00, z=30.84], EntityItem['item.item.eldritchScale'/1030, l='MpServer', x=322.34, y=54.13, z=63.16], EntityAspectOrb['Aspect Orb'/2827, l='MpServer', x=328.94, y=56.06, z=47.69], EntityAspectOrb['Aspect Orb'/2828, l='MpServer', x=328.68, y=59.06, z=44.77], EntityAspectOrb['Aspect Orb'/2829, l='MpServer', x=326.61, y=59.06, z=44.85], EntityOmotholGhoul['Omothol Ghoul'/2702, l='MpServer', x=309.19, y=34.00, z=102.17], EntityAspectOrb['Aspect Orb'/2830, l='MpServer', x=329.05, y=62.06, z=41.87], EntityRemnant['Remnant'/2705, l='MpServer', x=307.50, y=33.00, z=111.50], EntityRemnant['Remnant'/2706, l='MpServer', x=304.50, y=33.00, z=112.50], EntityOmotholGhoul['Omothol Ghoul'/2707, l='MpServer', x=296.50, y=33.00, z=107.50], EntityShadowCreature['Shadow Creature'/405, l='MpServer', x=307.50, y=42.00, z=80.16], EntityRemnant['Remnant'/2709, l='MpServer', x=333.50, y=45.00, z=80.50], EntityGatekeeperMinion['Minion of The Gatekeeper'/2586, l='MpServer', x=405.13, y=54.00, z=80.72], BlueSlime['Blue Slime'/2719, l='MpServer', x=345.00, y=104.88, z=-16.66], EntityRemnant['Remnant'/2080, l='MpServer', x=278.50, y=43.00, z=104.50], EntityShadowCreature['Shadow Creature'/2082, l='MpServer', x=319.75, y=37.00, z=40.50], EntityShadowMonster['Shadow Monster'/419, l='MpServer', x=331.47, y=49.00, z=62.69], EntityOmotholGhoul['Omothol Ghoul'/1451, l='MpServer', x=317.22, y=34.00, z=114.13], EntityRemnant['Remnant'/430, l='MpServer', x=336.50, y=43.00, z=56.09], EntityRemnant['Remnant'/431, l='MpServer', x=323.69, y=43.00, z=58.69], EntityOmotholGhoul['Omothol Ghoul'/1846, l='MpServer', x=303.03, y=29.00, z=105.38], EntityRemnant['Remnant'/2620, l='MpServer', x=329.47, y=49.00, z=60.04], EntityRemnant['Remnant'/2621, l='MpServer', x=336.50, y=44.00, z=61.50], EntityRemnant['Remnant'/2378, l='MpServer', x=330.69, y=53.00, z=67.69], EntityRemnant['Remnant'/1630, l='MpServer', x=266.50, y=33.00, z=121.50], EntityItem['item.item.tconstruct.strangefood.edibleslime'/2531, l='MpServer', x=344.94, y=105.75, z=-14.53], EntityItem['item.item.omotholflesh'/1510, l='MpServer', x=322.34, y=54.13, z=62.88], EntityXPOrb['Experience Orb'/2541, l='MpServer', x=327.25, y=53.25, z=86.16], EntityRemnant['Remnant'/2031, l='MpServer', x=326.16, y=66.00, z=34.50], EntityShadowMonster['Shadow Monster'/2802, l='MpServer', x=303.50, y=53.00, z=74.50]]
Retry entities: 0 total; []
Server brand: fml,forge
Server type: Integrated singleplayer server
Stacktrace:
at net.minecraft.client.multiplayer.WorldClient.func_72914_a(WorldClient.java:373)
at net.minecraft.client.Minecraft.func_71396_d(Minecraft.java:2444)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:919)
at net.minecraft.client.main.Main.main(SourceFile:148)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

I've gotten that crash as well. It's caused by a null check I forgot to add in the Remnant code, which makes the game crash when it attempts to remove a null entity from it's EntityAINearestAttackableTarget (used to tell the entity, in this case a Remnant, to attack the specified entity when one is spotted).

Fixed in 1.8.8 Beta

ive also received pretty much the exact same error message, the top line talking about a ticking entity remnant error, has there been a fix for it yet or any way i could make omothol playable because i have yet to even make it past the gate on my server since it just keeps crashing

Working towards getting a new version out today, since I've managed to patch all exploits related to a new feature. One thing related to an achievement hasn't been implemented (there's probably more than one case of this, but I'm focusing on one case specifically), which I kinda want to complete, so that's currently the thing keeping me from releasing the new stuff. Although, I could probably at least throw out a beta, since everything else is stable.