First official MMG minecraft DLC is here. This one is smaller. It adds new block. Enderum
It work's like bed. You right click it. And it will respawn you on top of it. But. If you break it and doesn't build anything near that spot. Your spawn point stays there.
Tip: If you breake Enderum, it will not drop itself but 8 obsidian and ender pearl
So. Yes rewards. When you respawn. Enderum will give you random item like endstone (most common), coal, iron, diamond and more. It have some cooldown so you cannot cheat the system.
Dimensional dump is a new dimension added by this mod. You get teleported here using enderum. Enderum have 1% chance to teleport you there after respawn. It's pretty dark dimension with endermans and 2 types of currupted endermans. You can find energy crystals there and complexes with great loot.
Only way of getting out of there is dying or building really easy portal with using dark matter onto frame from matter blocks.
Enderbeast and Ender Watcher
2 corrupted types of enderman. These can't teleport, are immune to water and are aggresive. These 2 types are also competetive between each other
Matter is essential component for first survival in Dump. It can be crafted into many things. Check JEI or NEI (I don't know which one is for 1.15)
Are randomly generated dungeons with lots of loot and spawners.
Overchests are small chests randomly generated in complexes with random loot. They can be mined and take somewhere else.