What It Represents Matters
Whether you vibrate the names of gods and spirits or the gods and spirits of a game. Technically it comes the same. The important part is, that your unconsciousness knows what they stand for, what they represent. So to know this we need to read through the lore of said represents.
Dwayna
The goddess of healing, air, warmth, and life
Melandru
Is the goddess of nature, earth, and growth
Lyssa
Is the twin goddess Lyss and Ilya of beauty, water, and illusion
Grenth
Is the god of darkness, ice, and death
Kormir
Is the goddess of order, spirit, and truth
Balthazar
The god of war, fire, and courage
Abaddon
God of water and knowledge
As you can see, each of these represents something. It's the same with most polytheism.
How Would I Go About It?
Once you know what something represents the best thing to do first is meditate over these. Whether you meditate over the planet of the day, the symbol of the planet, the spirit, the element, the zodiac sign or even the Chinese zodiac sign. This way you can attune to it and feel what its energy feels like. One would assume that the energy of Melandru feels way different than the feeling of Grenth, just like the feeling of earth feels different than ice.
The Downside of This
Depending on your confidence this may or may not work. Like I've mentioned several times the more you believe in something and the more others believe in the same thing the more likely it is to exist. So if you don't believe in this to work, it probably won't work. Even the smallest doubt can be fatal. At the same time, one would think since it's some gods from a game, most likely hardly anyone will believe in them being real, so technically one would assume that it's inefficient to work with these. However, I'd say if you use these energies and you feel comfortable using them then it might work wonders for you.Conclusion
After all the idea behind all this is something that many free mages and witches strive for:
"Find your own path, your own style."
References and More on the Topic
Here are some links to inform yourself about these gods and the religion of Guild Wars, if you're interested.