Reaper has 2 machines in it, and a few items. The Reaper Generator, which can generate energy from damaging nearby mobs and the Soul Beacon, which can use the souls in a soul crystal to give effects to mobs nearby     The Reaper Generator has 4 slots for runes. Each rune has a different functionality when inside the machine, and only a single rune is needed in order to activate its functionality:

• The Dilato rune will increase the current range of the Reaper Generator
• The Humano rune will enable the Reaper Generator to extract energy from hitting players
• The Obitus rune will enable the Reaper Generator to instantly kill anything
• The Reficiat rune increases the amount of energy generated per heart of damage dealt
• The Spiritus rune enables player only drops when the Reaper Generator kills an entity, but removes its ability to generate energy
• The Velocitas rune reduces the cooldown time between hits from the Reaper Generator
 

The Soul Beacon requires a similar structure to a normal beacon, where the 3x3 area under it (except the middle block) requires either a Soul Steel block or a rune block of some kind. The rune blocks functionality is as follows:

 
• The Dilato rune will increase the current range of the Soul Beacon
• the Beastia rune enables the Soul Beacon to hit neutral and passive mobs
• The Duplici rune will make the action of the Soul Beacon trigger twice in a cycle
• The Efficacia rune reduces the energy cost of the Soul Beacon
• The Hostilis rune enables the Soul Beacon to hit hostile mobs
• The Possessio rune will either prevent a particular player from being affected by the Soul Beacon, or adds that player to the whitelist of players who can be affected by the Soul Beacon