Spawning spiders, slimes & Magma cubes from dispensers suffocates them.

Confirmed, their hit boxes clip into the dispenser, sometimes(or all the time) keeping them from moving.

It sucks. I would have liked to use this mechanic in an adventure map.

I think it should be fine if you have the dispenser below where the mob spawnsw

Does MC-8293 describe your issue?

Not exactly tested it with the dispenser in the wall. There were no blocks behind or in front of it just on all the other sides

Is MC-8293 the same issue as yours? I am just looking for a yes or no answer.

It's a related issue, it's caused by the mob being spawned in a position with it's hitbox in a block.

dispenser == solid block

head/hitbox in solid block == suffocation damage

Is this still a concern in the current Minecraft version 1.7.2 / Launcher version 1.3.4 or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.

It probably is, but it was mainly used for adventuremaps etc, now you can use commands to spawn in mobs, so using dispensers for adventuremaps is a little redundant.

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