Accuracy X/-X: A cumulative, static ability that means, "Add X to each of this unit’s attack dice." and "Subtract X from each of this unit’s attack dice." respectively. Accuracy can’t alter "natural" rolls to affect Critical Hit, Fury, or Parry, but it can affect your chance against Armor. If a unit gets the Accuracy ability after you roll attack dice, it's too late to affect the hits.
Alternative Cost
Alternative Cost: [cost]: A selective, static effect that means, "Instead of paying the build cost of this card, you may complete this card by paying the [cost] listed." Alternative Cost must be paid in full, if it is not possible to pay the [cost] completely, you can't complete the card. You must pay the [cost] in the order listed. Any ability that reduces the normal cost to complete a card does not reduce the [cost] in that card's Alternative Cost, unless the ability specifically says so.
Armor
Armor: An isolated, static ability that means, "This unit can only be hit on a roll of 5 or more." Armor works against dice of damage and attack dice. It redefines what die roll is required to hit a unit. It doesn’t modify the die roll like Accuracy. A unit with Accuracy 1 attacking a unit with Armor hits with 4's, 5's, and 6's.
Backfire
Backfire X: A cumulative ability triggered by the initial dice roll that means, "When you roll at least one natural three with this unit's attack dice before re-roll, this unit does X dice of damage to itself when the attack ends." Backfire applies only to dice rolled for an attack, not to dice rolls for abilities like Retaliate.
Bombard
Bombard X: A cumulative, static ability that means, "This unit may attack a unit in the Ground arena instead of the Space arena, using X power plus any other effects." You choose whether to use Bombard to attack a unit in the Ground arena or to make a normal attack in the Space arena. You can't attack a unit in the Space arena using Bombard. Power changes affect Bombard.
Bounty
Bounty: [bonus]: A layered ability triggered during a unit discard that means, "When another unit is discarded by damage from this unit, you gain the following when your next build step starts." Bounty triggers even if the attacking unit leaves play. Bounty works in the build zone. You will gain the bounty even if the attacking unit is sent to the discard pile. The unit can't collect a bounty on itself.
Critical Hit
Critical Hit X: A cumulative ability triggered during the pending damage POP that means, "If you rolled at least one natural six with this unit's attack dice, this unit does X more damage for this attack." Only one natural "6" counts in the attack roll after re-rolls. If a unit gets the Critical Hit ability after you roll attack dice, it's too late to affect the damage. Accuracy can't increase the die roll to a natural "6". However, you or your opponent may use an effect to re-roll dice to affect the number of natural sixes. (You only count the six, if any, from the roll used for the attack.) Critical Hit applies only to dice rolled for an attack, not to dice rolls for abilities like Retaliate.
Enhance
Enhance: [Effect]: A selective, static effect that means, "You may play the following effect by paying the additional cost." The effect states whether you play it "instead" or "also". You must declare it to get its effect.
Evade
Evade X: A layered ability activated during the damage prevention POP that means, "Prevent up to X damage to this unit." You can play Evade only once for each instance of damage. You don't have to use all of the Evade. You choose how much damage to Evade up to X, even if the full amount of damage or more is pending.
Ferocity
Ferocity: An isolated, static ability that means, "Damage from this unit can't be prevented." Damage that can't prevented includes all damage coming from the unit with Ferocity, including damage from attacks, Ambush, Deflect, Retaliate, and other abilities. Units with Fortitude override this ability, and can prevent damage to themselves from units with Ferocity.
Fury
Fury X: A cumulative ability triggered by the initial dice roll that means, "When you roll at least one natural four with this unit's attack dice before re-roll, roll X additional attack dice." Only the first natural "4" counts. A four rolled after re-roll doesn't matter. If your unit gets the Fury ability after you roll attack dice, it's too late to roll additional attack dice. Fury applies only to dice rolled for an attack, not to dice rolls for abilities like Retaliate. Accuracy can't increase the die roll to a natural "4."
Hidden Cost
Hidden Cost X: A selective, static effect that means, "As long as you have a number of build counters on this card equal to X or the unit's current build cost (whichever is less), you may complete it anytime by paying Force for the remaining build cost, if any." Effects and stacking rules may reduce the build cost. You do not need to pay Force if the build cost is within the Hidden Cost integer. You can deploy it to the build zone. Hidden cost can only be played if the card is partially built and has the required number of build counters on it. You may use Hidden cost anytime, even during any Play-or-Pass chances not reserved for re-roll, damage prevention, or disrupt POP chances. If there are a number of build counters on the unit equal to or greater than the Hidden Cost integer, you do not need to pay any Force. You may not use Hidden Cost to deploy a Pilot to a unit.
INSERT
INSERT: A layered, static ability that means, "When this card is in play or stacked under the unit, the unit gets the following effect:" Insert works while in the build zone. The effect works while anywhere in the unit's stack. The granted ability remains to be the ability of its type. (For example, activated abilities granted by Insert may be disrupted.) The granted effect may not work in the build zone as per the rule for the rule for that effect.
Intercept
Intercept: A selective ability activated during the attack POP that means, "If one of your other units is being attacked in the same arena, the attacking unit now attacks this unit instead." Intercept doesn't end the attack. Any number of units may intercept an attack once for each instance of the effect. Each intercepting unit has been attacked. Intercept isn’t a prevention ability. Intercept doesn’t cause a new attack. (It is the same attack.) Your unit may intercept an attack from one of your own units (but not from itself) as long as that unit can attack it. If it can't attack the intercepting unit, you can pay its activation, but the defending unit won’t change. "For this attack" effects do not trigger for each intercept. Some effects may end because they don't apply to the new defending unit unless the effect's conditions are met by the new defending unit. An effect that addresses the attack can't be played for each intercept, but could continue.
Overkill
Overkill: An isolated ability triggered during the pending damage POP that means, "When this unit attacks, you may divide hits in excess of the defending unit's remaining health between that unit and another unit in the same arena." The player who controls the attacking unit decides how many hits (if any) in excess of the defending unit's remaining health to reassign as damage to the second unit. (That player can't change their mind afterward.) A number of hits equal to the defending unit's health must be assigned to the defending unit, and the remainder may be assigned to the defending unit or another unit in the same arena. Overkill damage is caused by the ability, not the die roll. Shields, Parry, and Armor have no effect against it, but damage prevention not specifying dice works normally. Both units resolve damage in tandem.
Pilot
[sub-type] Pilot: A layered, static ability written as "[sub-type] Pilot. The [sub-type] gets:… ." that means, "You may move this card onto or off of a non-Droid Space or Ground unit of the correct sub-type once during the build step. Ignore all other text on this card except its name, sub-type and health. The piloted unit can't have more than one Pilot." Treat all of a unit's Pilot abilities for a sub-type as a single Pilot ability for that sub-type. It grants abilities to that unit alone. See the "Pilots" section of the rules PDF for more info.
Precision
Precision: An isolated, static ability that means, "This unit cannot be intercepted." An attacking unit with Precision cannot have the target of its attack changed by a unit with the Intercept ability. "Elude" is the former name of this keyword. Treat any unit with Elude as if it has Precision instead.
Reserves
Reserves: [Ability]: A layered, static ability that means, "The following ability works while, and only while, it's in the build zone." The granted ability remains to be the ability of its type. (For example, activated abilities granted by Reserves may be disrupted.)
Shields
Shields X: A cumulative, static ability that means, "The attacking unit gets –X power against this unit." Shields only matters when attack dice are rolled. If you give a unit Shields after your opponent has rolled for damage, it doesn't affect the roll.
Stealth
Stealth: An isolated, static ability that means, "This unit can't be attacked unless it's tapped or has damage counters on it." An untapped and undamaged unit with Stealth can still be affected by alternative types of damage. (Such as Overkill.) As long as the unit has any number of damage counters on it, it can't use Stealth.
Switch
Switch: [1st/2nd/3rd type effect]: A layered, static ability that means, "As long as this unit is in the first arena listed on its type line, it gets the effects listed to the left of the first slash. As long as this unit is in the second arena listed on its type line, it gets the effects listed to the right of the first slash. As long as this unit is in the third arena listed on its type line, if any, it gets the effects listed to the right of the second slash, if any." If it says "None" as one of the arena type's effect, it means that it gets no extra effects while in that arena. The unit's Switch effects will correspond to the types listed on the unit's type line. There won't be a slash for an arena not listed in the unit's type. Switch doesn't allow units to change arenas during the battle phase.
Upkeep
Upkeep: [Cost]: A layered ability triggered when the build step starts that means, "When the build step starts each turn, you must pay the following cost." You must choose one of the costs that you can pay each turn, and ignore the others. You must still pay the Upkeep costs of a unit even if that unit is in the build zone, becomes the top card of a unique unit stack, or Pilots another unit. The Upkeep must be paid if you can pay it. If you can't pay any of the listed costs in full, then ignore Upkeep. If a unit has multiple Upkeep abilities, fulfilling just one of the Upkeep abilities (such as tapping the unit) does not satisfy all the Upkeep costs at once; it would only satisfy that instance of Upkeep. You may choose the order of multiple Upkeep abilities to keep an Upkeep from being paid, though a different order might pay it.