Fish's Undead Rising adds many hostile mobs and some cool items to Minecraft.
Here's the link to the mod page: https://www.curseforge.com/minecraft/...
Here's the link to the wiki if you want to know more about the mod: https://fish-undead-rising.fandom.com...

The mod version covered is 1.0.13 for Minecraft 1.12.2.

Timestamps:
0:00 - Intro
0:54 - Infected Zombie
1:20 - Foglet
1:40 - Sludge Lord
2:02 - Piranhas
2:29 - Swarmers
2:50 - Parasite
4:00 - Vespa
4:27 - Ptera
4:52 - OsVermis
5:17 - Raven
7:08 - Scarecrow
8:30 - Undead Swine
9:01 - Ithaqua/Wendigo
9:52 - Ingheta
10:13 - Penghouls
10:48 - Mimicrab
12:18 - Nether Salamanders
13:46 - Items

Credits:
The mod was developed by fish0016054.

Music used:
Strad Remix by Mauri -    / @makkaramauri5691  
(well looks like they changed their name!)