The game of Undercards has many unique abilities that come in two forms: Abilities attached with monsters and Effect Cards.
Effect cards, also known as Spell Cards, don't require a spot on the board to be used. There are 51 Effect Cards currently in-game, 7 for each of the 7 classes and 2 others.The Effect cards for the classes are devided in 3 Common, 2 Rare and 2 Epic in rarity. The other 2 cards are the Gaster Blaster (Legendary) and the Load Spell (DT), which can only be obtained through Sans/Gaster and Omega Flowey respectively.
Almost all monsters have an ability, each different from another. There are quite a few different methods of ativating these abilities:
- Can't attack: Monsters with this ability can not attack during their turn, even if they have 1 or more ATK. They are still able to do that damage while defending.
- There are currently no monsters with just this ability.
- Can't attack will not return if Silence is removed with Asriel.
- Charge: These monsters can attack right after being placed. Other monsters need to wait until the next turn in order to attack.
- Haste: This works the same as Charge, but monsters can't attack the enemy directly on the first turn.
- Taunt: Enemy monsters must target these kind of monsters. They can't attack any other monster or the player. Effect Cards are unaffected by it.
- Dodge: These monsters will take no damage from the number of turns shown on the card. The number will decrease by 1 whenever they should take damage. This will also reset at the start of the owner's turn.
- Armor: Monsters with this effect will have the damage they take reduced by the number of the card.
- Magic: These activate the moment you place them from your hand. Summoned monsters from cards like Igloo and Lamp don't activate it.
- This used to be Battlecry, followed by Enter.
- Dust: These activate once the monster that has it dies. Returning these monsters to the owner's hand or deck with cards like Doggo, Endogeny and Memory Head won't activate them. They also won't be activated if they die while being Silenced with the help of cards like Scarf Mouse or Nacarat Jester.
- This used to be Deathrattle, followed by Death.
- Future: These monsters have an ability that will activate after the number of turns shown on the card, like a delayed Magic effect. Silencing them won't stop the effect from activating.
- At the start of your turn...: As the name implies, these abilities activate at the start of every turn as long as the monster is alive and isn't Silenced.
- At the end of your turn...: These abilities function simmilar to the previous one, but will obviously activate at the end of every turn. This includes the turn in which they have been placed.
- Others: There are also abilities that don't follow any of these rules, but have their own way of triggering. Abilities like these include 'Whenever this monster is damaged...' or 'Whenever a monster is summoned...'.