Most useful powers | Vampiric powers DARK Guide
Last update: 11 May 2016
All of the suggestions published below are about playing the game exactly how it was planned by its creators. It means that you shouldn't avoid having contact with enemy units entirely and that aside staying in the shadows you should be silently eliminating all of your opponents (or at least most of them). I don't recommend trying to finish the game without killing hostile beings, because the game won't reward you for these efforts in any way. Furthermore, the only way to regain Vitae energy needed to activate more advanced vampiric abilities is to feed on your opponents and each feeding ends with a kill.
One of your first purchases should be Shadow Kill ability, because by unlocking this power you'll guarantee yourself a way of eliminating enemy units from a distance. This ability in its basic form is more useful than Shadow Grip. The second of the mentioned powers becomes much powerful on the other hand when it's fully developed, because it allows Eric to automatically get rid of the bodies. This patent is especially helpful if a guard is standing under a camera or somewhere else where it's hard to attack him and to dispose of the corpse.
Investing in teleportation (Shadow Leap ability) right from the start of the game is also a good idea. The upgrades are very handy, because not only they allow you to use teleportation without being heard, but they also increase the effective range of this skill. You'll notice the difference almost right away after each purchase, because being able to safely transport the main character to upper balconies or behind good covers will allow you to plan and execute your silent kills with a lot less to worry about.
Don't forget about other inherent powers - improving Instant Kill will allow you to lower the chances of being discovered while performing standard executions and purchasing upgrades for Feed will improve your safety when drinking someone's blood and as a result will give you a chance to use advanced powers more frequently.
As for the available passive powers, you should take interest in Assassin. Don't be fooled by a weak basic bonus, because each of the three upgrades of this ability offers extremely useful bonuses to sneaking and staying hidden. You should also consider acquiring at least the basic version of the Vitae ability, because you'll gain access to an additional Vitae point.
Once you've advanced further in the game start unlocking new upgrades for the powers mentioned above, making them even stronger. As for entirely new abilities, I recommend that you take interest in Auspex (being able to find ghouls and cameras will certainly help you), Distract & Domination (distracting and confusing enemy units is helpful from time to time) and Obfuscation (becoming partially invisible can save you on more than one occasion).