It can only be obtained from consuming Splattershrooms or by defeating certain enemies in TENGOKU (3 Bloodnium for a red-named Hater, 1 Bloodnium for a normal Hater).
The smallest Splattershroom variant. Gives 10 Bloodnium to the player upon consumption. May be found lying around in the Tower of Barbs.
The mid-tier variant of the Splattershroom. Gives 100 Bloodnium upon consumption. Once the 50th floor is unlocked, a weekly quest will be unlocked which rewards the player with 3 Big Splattershrooms for reaching the 60th floor. Additionally, Big Splattershrooms may be found anywhere on the Tower of Barbs.
The largest possible variant of the Splattershroom. Gives 1000 Bloodnium upon consumption. A weekly quest may be unlocked which gives the player 1 Mega Splattershroom for climbing to the 80th floor of the Tower of Barbs. This quest may be unlocked by finishing the "Climb to the 60th floor" quest. There's a very low probability to find this type of splattershroom inside of the Tower of Barbs. https://i.redd.it/hwr66wr2c9061.jpg
- “Take your max leveled Fighters to the Mingo Head and break their current limit. Use the Bloodnium and Death ‘Roids you’ve collected in 50+ floors to strengthen them even more. In addition to stat boosts, you can also increase your Fighter’s decal slots and Death Bag inventory size. Unleash the true potential of your Fighters!”
- — Uncle Death
Using Bloodnium and Death ‘Roids, you can uncap a Fighter's levels to 30 in each stat. Additionally, once all of their stats are level 30, they may then be uncapped further to level 35, and it can be uncapped one more time to 40.
Bloodnium may be used to purchase some high-level equipment and materials from the Hernia. This shop restocks at 10:00 UTC every day.