This is that boss from Yoshi's Island in World 6-4, now ported over to SMW. Having already been ported over back in March/April 2010 and used in ASMWCP's World 8, and even being released unofficially, it is now time to put this boss into the custom sprite section, where it belongs.
Information on insertion can be found in the readme. This pack comes with a version that uses the spike hell sprite (original), but also one that doesn't. Requires the No more sprite tile limits patch.
Updated so graphics no longer need to be manually inserted with a patch.
Tester's note: When the lava is placed too low, the level may not end. If for some level design reason the lava HAS to be placed low, use a level ender sprite or such to end the level properly.