The next critical question is: How is the energy collected?
We will discuss two major modes of use: Active and Passive collection. An active collection means that the caster must make an effort to gather or draw the energy from the source. A passive collection means that the caster simply uses the energy that is available.
Besides residing within the living beings themselves, life energy is radiated out into the environment. The radiated life energy of living organisms in a given locale collects in pools and streams just like water. There are two methods of accessing life energy. Naturally, a magician is not limited to strictly using one or the other, although they will generally prefer one or the other. Unlife works along exactly the same lines, gathering in dark pools and streams. Since it follows slightly different rules, the pools and streams will never be found in exactly the same locations.
Use it Passively
Passive life-force users cannot gather energy up to store it for later. A passive collector’s only source of power comes from the “pool and stream” sources.
Collect it Actively
Active life force collection involves draining the life from otherwise living creatures and plants. While death of the subject is not strictly necessary, it can be a side effect, and releases the most energy in the smallest amount of time.
The active collector can also make use of the “pool and stream” resources to avoid actually affecting living things.
Since any magician gaining their energy from a third party is given their energy rather than collecting it, the nature of that “gift” defines their power usage. The variations are nearly endless.
Arcane Energy and Dark Arcane Energy
The Arcane Energy field exists everywhere, at essentially unlimited levels. The magician using the Arcane Energy field simply draws energy from the field to accomplish their affects. These magicians are, for all intents and purposes, always passive.
Enchantment and Dark Enchantment
This presents an interesting case, as the true answer is “they don’t”. An enchanter does not gather or use energy directly at all. Rather, they craft and shape materials together to produce a new object or item that has particular properties. They could be considered a special case of passive use.
A magician using mental energy is drawing on an essentially unlimited power supply from within themselves. Mental energy is not stored, gathered, or pooled. It cannot be transferred. These magicians are completely limited to passive use.