Using [X] From the Shadows to teleport on top of the Spike as an Attacker, allows you to quickly pick up the spike, cancel your teleport, and out maneuver your opponents to plant the spike somewhere else on the map.
In the majority of situations,[E] Dark Cover should be placed so that it's flush with the entrance into the area of the map enemies are coming from. There should be no space for enemy players to lurk inside and peak from an unpredictable angle if they swing out of the smoke.
Omen's [C] Shrouded Step is great for catching people off-guard from unexpected locations like the top of boxes, corners, and otherwise impossible to cross sight lines.
Communicate when you will be using your [Q] Paranoia to maximize the impact it has within the round, and set up your teammates for success.