What is Spell Damage in Hearthstone?
Hearthstone has many card effects that are common enough that they get their own keyword - a word or two that immediately tells you how the card works. Let's take a look at the Spell Damage keyword.
Your spells deal extra damage.
Spell Damage is a mechanic that will boost the damage of your spells by a specified amount. Usually, this amount is 1, although other cards can boost it by more. Spell Damage is extremely powerful in combination with AoE, extending its reach. Spell Damage is most commonly associated with Mage and Shaman, although there are a lot of Neutral cards that use the ability as well.
Keywords that Work Great with Spell Damage
As your opponent will typically try to get rid of any Spell Damage minions you have right away, effects that increase its survivability such as giving it Divine Shield can be useful. Summoning Taunt minions will also protect it from attacks, although it will stay be able to be targeted by spells and Hero Powers through it.
Playing Against Spell Damage in Hearthstone
Spell Damage is typically only limited to a select few classes in its playing, meaning you will only need to think about Spell Damage in a select few cases. As your opponent will typically play the smallest Spell Damage minions available to them (to be able to use as many spells as they can with it), most Spell Damage minions that your opponent will play are generally not very hard to kill.
Example Hearthstone Spell Damage Cards
Wrath of Air Totem is one of the four Totems that can be summoned by the Shaman's Hero Power, Totemic Call, immediately giving you a source of Spell Damage which is often very useful in Shaman which tend to use a fair amount of damage spells, and it's strong with board clears.
Bloodmage Thalnos is one of the most notable cards in the game for being a "reverse noob trap". New players will often look at this card and feel underwhelmed, although it's actually very strong in several decks.
Cosmic Anomaly is a card that will give you Spell Damage +2, which is a pretty significant buff, especially for AoE effects.
Malygos is a strong Legendary often used in spell combo decks, granting you Spell Damage +5 which is the highest of any card in the game.