Malum

Malum adds a couple new things to spice up your worldgen.

The Runewood Trees are the most notable addition to world generation. 

They are huge magic trees that spawn in forests and more even more so, plains. Their gorgeous gradiented leaves and arcane design make them stand out quite well.
The tree tends to form a type of holy sap, you may find it exposed on some of it's bark. Once revealed, it can be collected using a glass container. The rejuvenating substance can be used to produce sapballs and can be heated up into solar syrup.
Wood from this tree will be one of the two things you need to start your descent into spirit magics.

Soulstone is a new ore that generates within the overworld, created with spirit arcana meets carbon based minerals.

As expected, it spawns on similar levels of diamond and coal veins.
This cursed gem will be the second item you need to become a spirit hunter.

"What is a spirit?" You may ask. A spirit is a magical element found within every living soul, they are the key material and mechanic present within Malum. When you strike an enemy you destroy the vessel of a soul. However, if you manage to hurt the soul and the vessel all at once you'll be able to completely eradicate your victim's arcane presence, leaving their soul shattered. This cruel method is the main source of obtaining spirits.

Spirit Harvesting is the first step into spirit arcana you will take.
Each living soul contains it's own unique set of spirits, of which there are many types.
The most primitive means of harvesting spirits requires a crude scythe, a novice weapon made from soulstone and iron. Final blows with a scythe will succesfully shatter your opponent's soul, resulting in spirits.
Scythes aren't just a tool though, they're a proper weapon. They grant the wielder enhanced sweeping capabilities at the cost of attack speed. 
They also come with their own enchantments, rebound for example allows you to throw your scythe like a boomerang.

Spirit Infusion is a process that takes place at the Spirit Altar, an arcane workbench of sorts. 
Spirit Infusion requires a prime item placed directly on the altar, a set of spirits surrounding the prime item and any additional items an infusion recipe may require. 
Additional items must be placed on item pedestals or stands, which can be made from most building blocks within Malum.

Malum not only adds things needed for it's progression, there are also some miscelanious additions.

Blazing Quartz for example is a fiery gem found within the nether realm.

It's a simple mix between coal and quartz, functioning as a good fuel and experience source while also being utilized in some magic crafting recipes.

Brilliant Stone is a somewhat uncommon vein of solidified experience, as you may know it.

Chunks derived from the ore can be turned into experience potions, or even 'eaten'..? yielding the exact same result.

If you'd like a more throughout review of the mod, check out the Mischief of Mice video! 

- Can I use the mod in a modpack?

Yes

- Will you port the mod to X/Y/Z version/modloader?

The mod will stay up to date with the latest version of the forge modloader, that isn't changing.

- How can I add custom spirit infusion recipes or spirit data?

Unfortunately I haven't made an official guide for malum's json systems quite yet. You can join the discord server and I'll tell you everything you need! If you're feeling generous you could maybe even help me write the guide :)

- Is the mod configurable?

Yes! I try my best to make as much as I can configurable inside of Malum. There are some bounds to this but if some config option you'd like is missing you can ask me to make one!

- Is 1.16.5 supported? 
No. The mod exists there however bugs will not be fixed nor will the version receive updates. 

I also do not encourage you to use it, I think those versions are quite dated.