There will be variable forms of stealth and evasion type skills.
One form being total or partial invisibility by bending light. The effectiveness depending on the skill or quality of device used. Using this method is still somewhat dangerous as the player will still be able to take damage from various sources such as AoE. You will still be able to attack in this state.
Another method of stealth will be phase inversion that actually momentarily takes the player out of the prime physical plane of existence. This means you are totally separated from everything else and will be both unable to attack or take damage (unless someone else just so happens to be in the same phase as you).
We are toying with the idea of having phase tech allow limited passage through otherwise solid substances such as walls or barriers.