Some troops and Warlords have Traits with different effects and triggers. Here’s a list of all Traits:

Backlash: Does something when dying.
Bastion X: Absorbs up to X damage received by this unit, with the only exception of damage taken when this unit is attacking.
Berzerk: Must act every turn.
Blood Thirst: Can act twice per turn.
Battle Honour: Does something after attacking if it kills an enemy and survives.
Can’t attack: Unit can’t attack.
Cleave X: When attacking, deal X damage to units adjacent the target.
Courage: Does something when played from hand if your opponent has more units.
Daemonhost: Gains a random buff and becomes a Daemon in addition to its current category.
Drop Pod: Protects this unit from damage until your next turn or until destroyed.
Duplicitous: The enemy Warlord can’t target this troop until it attacks, unless it has Front Line.
Fast: Can act on the same turn it comes into play.
First Strike: Unit does not receive damage from a unit killed while attacking.
Flank: Can act on the same turn it comes into play, except to attack the Warlord.
Front Line: Enemies must attack this unit, unless it also has Stealth.
Jam: Cancels all card abilities and active effects on a troop. You can apply new effects on a jammed troop normally, and it can be jammed again.
Landing: Does something when exiting a Drop Pod which hasn't been destroyed.
Maintenance X: While in play, reduces your available Energy at the start of your turn.
Mark of Chaos: A non-daemon Troop gains a random Chaos blessing. With 4 Marks, its become a Greater Daemon.
Mission: Special type of Tactic that is always drawn in the starting hand of the game if it's included in the deck. When played, it gives an objective that will grant a reward if it is ever completed.
Mutation: Choose a daemonic buff. Reduce Maintenance by 1.
Pack: Does something when another friendly unit attacks.
Perfection: Does something if playing this card spends all remaining Energy.
Pilot: Knight Houses warlords must choose a Pilot that will set the ability, heraldry and chat options of the Warlord.
Poisonous: Applies Poison to troops damaged in combat. A Poisoned troop dies at the end of its turn.
Precognition: Unit cannot be attacked.
Psyker X: Gain X Psychic Energy at the start of your turn.
Rage: Does something when damaged, even after receiving lethal damage. If receiving lethal damage, further damage won’t trigger rage.
Rally: Does something when played from hand.
Reactor X: Gain X Plasma Energy at the start of your turn.
Quest: Choose a secret Quest. Complete it to trigger an effect.
Reflection: Can be played multiple times during the same turn.
Relentless: Does something at the start of its turn.
Requiem: Does something when an adjacent troop dies.
Sacrifice: Does something when this unit attacks and gets killed by the defender (even if it gets saved by Survivor)
Sentenced X: After taking damage, a unit takes then X additional damage.
Sentinel: Player controlling a unit with Sentinel will not draw a card at the beginning of their turn.
Shield: Absorbs all damage from one attack or effect.
Siege: Ability will not do anything after being used for the first time; instead, it will allow you to use it next time you play it.
Stealth: Unit cannot be attacked or targeted until it enters combat. Using active abilities doesn’t break stealth. Applying Stealth to a Front Line unit denies the Front Line effect until Stealth is broken.
Streak: Does something when played from hand if this is not the first card played this turn.
Stun: A stunned unit misses its next turn.
Survivor X: Instead of dying, get back to X health and lose this ability. Only triggers when the unit is killed with damage, not ‘destroyed’ or killed with ‘Poison’.
Terror: When attacking, troops with lower Attack don't retaliate.
Unstoppable / Flying: Can ignore Front Line units when attacking.
Ward: Can’t be targeted by enemy abilities. Enemy abilities that choose targets randomly can still affect units with Ward.
Wing: Dark Angels troops can belong to the Deathwing, the Dreadwing or the Ravenwing. These have no effect by themselves, but can trigger additional effects in other cards.