A cover hex is a hex, often with low energy cost and fast recharge or Area of Effect, which is used after another hex on the same target. This makes it more difficult for the enemy to remove the first hex, as most hex removal skills only remove the most recent.
See hex removal skills quick reference for a list of skills that remove hexes.
Frequently used cover hexes[]
Life Siphon
Parasitic Bond
Suffering
Faintheartedness
Defile Defenses
Ether Phantom
Images of Remorse
Mind Wrack
Wastrel's Worry1
Wastrel's Demise
Shrinking Armor
Conjure Phantasm
Fragility
Web of Disruption
Recurring Insecurity (elite)
Elemental Flame
Mark of Rodgort
Rust
Enduring Toxin
1Only works against Holy Veil or hex removal by a third person, as other hex removal would require the use of a skill, which will cause Wastrel's Worry to end first and then remove the second hex.