Minecraft CurseForge

This issue  has occurred multiple times where the server crashes during some combat event. I don't know much about running a server and don't know the exact cause of the crash. If someone could point me in the right direction that would be great. I have attached relevant information from the crash report. 

-- Head --
Thread: Server thread
Stacktrace:
	at java.util.Random.nextInt(Random.java:388)
	at com.windanesz.ancientspellcraft.handler.ASEventHandler.onLivingHurtEvent(ASEventHandler.java:437)
	at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_1227_ASEventHandler_onLivingHurtEvent_LivingHurtEvent.invoke(.dynamic)
	at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90)
	at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:182)
	at net.minecraftforge.common.ForgeHooks.onLivingHurt(ForgeHooks.java:604)
	at net.minecraft.entity.player.EntityPlayer.func_70665_d(EntityPlayer.java:1120)
	at net.minecraft.entity.EntityLivingBase.func_70097_a(EntityLivingBase.java:926)
	at net.minecraft.entity.player.EntityPlayer.func_70097_a(EntityPlayer.java:1038)
	at net.minecraft.entity.player.EntityPlayerMP.func_70097_a(EntityPlayerMP.java:645)
	at net.silentchaos512.scalinghealth.event.DamageScaling.onPlayerHurt(DamageScaling.java:95)
	at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_2170_DamageScaling_onPlayerHurt_LivingAttackEvent.invoke(.dynamic)
	at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90)
	at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:182)
	at net.minecraftforge.common.ForgeHooks.onPlayerAttack(ForgeHooks.java:591)
	at net.minecraft.entity.player.EntityPlayer.func_70097_a(EntityPlayer.java:994)
	at net.minecraft.entity.player.EntityPlayerMP.func_70097_a(EntityPlayerMP.java:645)
	at com.github.alexthe666.iceandfire.entity.IafDragonDestructionManager.destroyAreaFire(IafDragonDestructionManager.java:46)
	at com.github.alexthe666.iceandfire.entity.EntityFireDragon.stimulateFire(EntityFireDragon.java:364)
	at com.github.alexthe666.iceandfire.entity.EntityFireDragon.shootFireAtMob(EntityFireDragon.java:275)
	at com.github.alexthe666.iceandfire.entity.EntityFireDragon.func_70636_d(EntityFireDragon.java:154)
	at net.minecraft.entity.EntityLivingBase.func_70071_h_(EntityLivingBase.java:2179)
	at net.minecraft.entity.EntityLiving.func_70071_h_(EntityLiving.java:295)
	at com.github.alexthe666.iceandfire.entity.EntityDragonBase.func_70071_h_(EntityDragonBase.java:1463)
	at net.minecraft.world.World.func_72866_a(World.java:1996)
	at net.minecraft.world.WorldServer.func_72866_a(WorldServer.java:832)
	at net.minecraft.world.World.func_72870_g(World.java:1958)

-- Entity being ticked --
Details:
	Entity Type: iceandfire:firedragon (com.github.alexthe666.iceandfire.entity.EntityFireDragon)
	Entity ID: 520
	Entity Name: Fire Dragon
	Entity's Exact location: -653.97, 64.00, 510.63
	Entity's Block location: World: (-654,64,510), Chunk: (at 2,4,14 in -41,31; contains blocks -656,0,496 to -641,255,511), Region: (-2,0; contains chunks -64,0 to -33,31, blocks -1024,0,0 to -513,255,511)
	Entity's Momentum: 0.05, -0.08, -0.10
	Entity's Passengers: []
	Entity's Vehicle: ~~ERROR~~ NullPointerException: null
Stacktrace:
	at net.minecraft.world.World.func_72939_s(World.java:1762)
	at net.minecraft.world.WorldServer.func_72939_s(WorldServer.java:613)

-- Affected level --
Details:
	Level name: Biome Bundle
	All players: 1 total; [EntityPlayerMP['ZacharyW'/323, l='Biome Bundle', x=-653.24, y=63.00, z=507.47]]
	Chunk stats: ServerChunkCache: 563 Drop: 0
	Level seed: -8208410740112575810
	Level generator: ID 11 - OTG, ver 0. Features enabled: true
	Level generator options: OpenTerrainGenerator
	Level spawn location: World: (-652,71,1000), Chunk: (at 4,4,8 in -41,62; contains blocks -656,0,992 to -641,255,1007), Region: (-2,1; contains chunks -64,32 to -33,63, blocks -1024,0,512 to -513,255,1023)
	Level time: 8173821 game time, 9278069 day time
	Level dimension: 0
	Level storage version: 0x04ABD - Anvil
	Level weather: Rain time: 77858 (now: false), thunder time: 62394 (now: false)
	Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
Stacktrace:
	at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:767)
	at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:397)
	at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:668)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:526)
	at java.lang.Thread.run(Thread.java:748)