Power Siphoning

Power Siphoning is a unique form of magic which takes on many forms. Universally speaking, it has the ability to siphon a being's magical power and either cause it to dissipate or transfer it to another being and/or object. While a powerful magic, only those well-versed in it can use it, and only those more powerful than their target can use it efficiently and permanently.

Cutie Mark Siphon
Seeing as how Cutie Marks contribute to a pony's destiny, and that destiny contributes to their magical ability, stealing a pony's Cutie Mark is considered a type of power siphoning.

Direct Siphon
A type of siphoning used to great effect by Tirek, this siphoning is very simple in that it directly steals the power from one being and transfers it to another. This power can only be used by the Embodiment of Greed.

Seal Siphon
This was the type of magic used to seal Malevolence in stone and siphon her power for use by Astral. It is unique in that it is a long-term type of siphoning that can be maintained as long as it has some form of magic powering it.

Transfer Siphoning

The Ancients are known to pass on magical power through the use of objects. One well-known case of this was in sealing the power of Chaos in a gem. This power was later 'gifted' to Discord in an attempt to drive him insane and eliminate him as a potential threat, however this backfired when he learned to control it.