This happened on my locally hosted server. I placed a Draconic tier Stabilized Mob Spawner in my mob grinder room and the game instantly crashed. At the time of placing the block, the gamemode was set to peaceful. The mob spawner was either a Blaze or a Magma Cube. It happened in the overworld. I have placed Draconic tier Stabilized Mob Spawners down before in the same area. I have tried restarting both the client and the server and I still crash when I'm about to enter the game, though the server is unaffected.

Here is the crash log: http://textuploader.com/d685p

Does this crash occur if the game is in non-peaceful mode?

Please describe your mob grinder room. What other machines are present? Also, if you rollback the server to last previous backup and try placing other Draconic tier Stabilized Mob Spawners with other mobs elsewhere, does it cause this problem? If you try placing a Draconic tier Stabilized Mob Spawner with a Blaze or a Magma cube elsewhere does it cause this problem?

Thank you.

This appears to be a problem with a tessellating block during rendering. I snipped out these bits which seem most relevant (learning a tiny bit about MC troubleshooting but not much):

Description: Tessellating CCL block in world

-- Head --
Thread: Client thread
Stacktrace:
at java.nio.Buffer.checkIndex(Unknown Source)
at java.nio.DirectByteBuffer.putFloat(Unknown Source)
at net.minecraft.client.renderer.BufferBuilder.func_187315_a(BufferBuilder.java:347)
at codechicken.lib.render.CCRenderState.writeVert(CCRenderState.java:187)
at codechicken.lib.render.CCRenderState.render(CCRenderState.java:167)
at codechicken.lib.render.CCModel.render(CCModel.java:460)
at codechicken.lib.render.CCModel.render(CCModel.java:448)
at cofh.thermaldynamics.render.RenderDuct.renderBase(RenderDuct.java:176)
at cofh.thermaldynamics.render.RenderDuct.renderBlock(RenderDuct.java:394)
at codechicken.lib.render.block.BlockRenderingRegistry.renderBlock(BlockRenderingRegistry.java:90)

-- Block being tessellated --
Details:
Block type: ID #1095 (tile.cofh.duct // cofh.thermaldynamics.block.BlockDuct)
Block data value: 3 / 0x3 / 0b0011
Block location: World: (97,71,415), Chunk: (at 1,4,15 in 6,25; contains blocks 96,0,400 to 111,255,415), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Stacktrace:
at codechicken.lib.render.block.CCBlockRendererDispatcher.func_175018_a(CCBlockRendererDispatcher.java:52)
at net.minecraft.client.renderer.chunk.RenderChunk.func_178581_b(RenderChunk.java:296)
at net.minecraft.client.renderer.chunk.ChunkRenderWorker.func_178474_a(ChunkRenderWorker.java:119)
at net.minecraft.client.renderer.chunk.ChunkRenderDispatcher.func_178505_b(ChunkRenderDispatcher.java:174)
at net.minecraft.client.renderer.RenderGlobal.func_174970_a(RenderGlobal.java:1458)
at net.minecraft.client.renderer.EntityRenderer.func_175068_a(EntityRenderer.java:1700)
at net.minecraft.client.renderer.EntityRenderer.func_78471_a(EntityRenderer.java:1590)

I rolled back to a previous backup and could not replicate the bug. The things present were 9 other Draconic Stabilized Spaweners from Draconic Evolution, a single Mob Grinder from Draconic Evolution, an Environmental Controller from RFTools with No Enderman Teleport Module installed, Item Collector from Cyclic, Experience Solidifier from Actually Additions, some Fast Slime Conveyors on the floor, Signalum Fluxducts form Thermal Dynamics to power the machines, and Signalum Plated Impulse Itemducts from Thermal Dynamics to carry the collected items away, all contained within a 10x8x10 box of Thickened Glass.

I tried replicating the bug on an offline Superflat creative world (and toggled between gamemode 0 and 1) but experienced no crash.
Thanks for helping.