So you're writing a book, eh? As am I, and writing is a great thing. Though I realize you found a good answer to your question, I have learned in my fairly short time writing that it never hurts to have additional ideas up your sleeve. Writing is a long, hard process, so without further rambling here are some ideas. Environmental/Elemental drain- This is the ability to absorb energy from your environment. If you're leaning toward fantasy logic, this includes fire water/ice, earth, nature, lightning, light, and darkness. If you want to be more scientific, it applies only to fire, lightning, and light. This would allow the drainer to absorb the energy from whatever they absorbed and use it accordingly, whether for healing wounds, replenishing energy, or using an attack. At a higher level, this can be used to drain energy and even life force from opponents for personal use. Mental Subjugation- This involves taking control over the actions of a target. At this point, they are yours to control until your energy is depleted. Advanced users of this technique can control many at once, or use a toned down version of it on allies to coordinate strategy or help them avoid attacks. This can also be used in conjunction with necromancy to resurrect and control the deceased. If used on a resistant target, the user would actually have to enter the mind of their target and manually dismantle their consciousness. This can make for some cool inner fight scenes. Darkness Manipulation- I know, its very common, but darkness if fun to work with. If you want to be more scientific, you probably won't want it. If not however, darkness is a powerful energy that can be used for direct attacks, constructions (swords, shields, claws, pillars, etc.) Darkness is usually drawn from past turmoil, or is sometimes inherited through blood. It is usually associated with negative emotions, but not always. Weapon/item transformation- Say you had a knife made of extremely dense metal. If you had the power to change its shape, there would be enough matter to form a sword or possibly even a hand axe, depending on its density of course. This would allow the user to use one weapon, yet have it serve the purpose of any weapon or tool. This can also be extremely useful for lock picking. Remember, this is only changing the form of the matter that exists. Converting or creating matter would be much more difficult. Dimensional offense/defense- This I would recommend only for character who are meant to have incredible control over dimensional power. The user would use some sort of punch, slash, or kick, and while doing so break a dimensional hole (or portal) from one place to another. The attack would then proceed to move through the portal and hit the target on the other side of the portal. This can also be used to create portals for the sake of avoiding attacks or warping opponents. If you decide to use this, do so sparingly, as it can be insanely book breaking having a character who can manipulate dimensions to his will unless a restriction is placed. Sacrifice- This can be used in many different ways. The first is sacrificing some of your life force or a large amount of energy to enhance your capabilities or the capabilities of others. Thanks to its wide range of uses, it could be wielded by a tactician or a berserk, or even a healer. Despite this, there are many other dacrifices that can be executed to gains more power. Anything for blood to whole appendages could be sacrificed to gain combat advantage. I know it sounds unsettling, but some forces (ex. evil, extremists, cultists, anarchists, etc.) will stop at nothing to win a fight and change fate. Time Travel- Hey! You're using this one! Its extremely fun, and can make plots very interesting, but i warn you. Plot holes can come up all the time so beware. Also remember to have some fun with it. Take time to plan out which past dwellers characters will meet and how it will effect their lives. Also consider differences in culture and government, and for God's sake! Don't end up erasing the entire story or the universe! Please! More than anything, make a story that you really love. If you do, I'll read it, I promise. Even if Its not my genre (even though it probably is). If this helped in ANY way, message me and maybe I can toss you some more ides. As a fellow writer, I think we could get along well. So enjoy the experience and keep going. Even if you think it won't work or someone tell you its stupid never give up. The more you write the better you get, so try to experiment with new ideas. Now enough of my rambling, I hope you have a great day and that you continue writing, so I'll see you around on the internet.