Mage
Give each spell a job: remove a threat, buy time, find cards, or win the game.
What the class does
Mage uses spells for many jobs. A spell may kill a minion, damage the enemy hero, or stop attacks for a turn. The same spell might keep you alive now or win the game later.
Think about why you need the spell, not just what it costs.
Use damage carefully
Damage spent on a minion cannot also hit the hero. A small damage effect may finish a minion and let you save a bigger spell.
Freeze buys time but may leave the threat alive. Plan for the turn when that frozen minion can attack again.
Choices to think about
Count all your damage before using a spell with several possible targets. Include damage boosts, and check which targets each spell can hit.
If you plan to draw or create a card, doing it early may reveal a better play. Save enough mana to use a helpful result. A full hand of cards you cannot play will not fix the board.
Strengths and weak spots
Mage can change a spell's job as the game changes. But you may need the same damage for both defense and a win. Buying time is useful only if you can turn that time into a better position.
See Deck Types for general game plans such as aggro, control, and combo.
The linked class guides explain the main rules and older class themes. This wiki supplies the play examples. For exact card details, use current card text and patch notes.