Legends of Runeterra is the new free-to-play online card game from Riot Games and part of the League of Legends series set in the same universe. In this game each card will have Keywords on it. The Keywords refer to specific mechanics that exist in Legends of Runeterra, and there are many of them.

The game does a great job explaining each of the different keywords with tutorials, so you can play through those to get a better understandings. This guide outlines all of the different Legends of Runeterra keywords along with a description of each of them.

Legends of Runeterra Keywords

Keyword Description
Allegiance Activates when the top card of your deck is from the same faction as this unit.
Attack Triggered when unit is attacking.
Aura Effect applied when unit is on the board.
Barrier Become invulnerable until damage is taken.
Burst Spells Resolves instantly and doesn’t consume an action, allowing another card to be played immediately.
Can’t Block Unit cannot block enemy attacks.
Capture Unit is removed from play until the captor is removed from play.
Challenger Choose which enemy blocks this unit.
Double Attack Strike twice against the blocker.
Drain Deal and heal allied Nexus.
Elusive Can only be blocked by other Elusive units.
Enlightened Activates at 10 mana, players gain a max mana gem every turn.
Ephemeral Unit dies when it attacks or at the end of the turn.
Fast Spells Can be played in response to Spell cards and may be used during battle phase.
Fearsome Can be blocked only by enemies with 3+ attack.
Fleeting Discard from hand when round ends.
Frostbite Set a unit’s power to zero. Can be increased by spells and effects.
Imbue Triggers when resolving a spell
Last Breath Triggered when unit dies.
Level Up A condition that levels up the card.
Lifesteal Damage dealt heals your Nexus.
Nexus Strike Triggers when unit attacks Nexus.
Obliterate Completely removed from the game. Does not trigger Last Breath or any
other death effects and cannot be revived.
Overwhelm Overkill damage spills over to the nexus.
Play Occurs when a card is played from your hand.
Quick Attack Strikes first before the blocker but only in attack phase. 
Rally Get on the offensive. Gain an attack token if you do not have one.
Recall Return a unit to your hand and remove all effects applied on it.
Regeneration Heals at the beginning of each round.
Skill A spell effect created and cast by the unit.
Slow Spells Cannot be cast during battle phase and takes a turn to prep.
Strike Occurs when a unit deals combat damage.
Strongest Highest Power, ties determined by highest Health then highest Cost.
Stun Remove unit from combat, and it cannot attack or block for the rest of
the round.
Support Buffs the unit to the right. Only applies when the unit is attacking, not permanently.
Tough Take one (1) less damage from all sources. Calculated after Barrier.
Trap Attached to a card in the deck. Effect is triggered when card is drawn.
Trigger Effect triggered when a condition is met.
Weakest Lowest Power, ties determined by lowest Health then lowest Cost.

Those are all the Legends of Runeterra Keywords for now, though many more are expected to be added frequently. We’ll do our best to keep this list up to date and accurate so you can use it for reference.