Conceal is a Rogue spell card. Its effect is to give your minions stealth, which makes them untargetable by attacks and targeted spells/effects. They still take damage from Area of Effect spells/effects, and can still be hit from spells that hit a random target. Stealth received from Conceal is removed after the minion attacks or at the beginning of your next turn. Taunt is disabled on any of your stealthed minions.
Conceal is most commonly used as a way to protect your valuable minions by preventing your opponent from stacking them with his own minions, weapons or by casting spells on them (however, they can still be hit by area of effect spells like Flamestrike/Hellfire or random target spells like Flamecannon.
Conceal was and still is a core spell used in Miracle Rogue decks - it is used to stealth Gadgetzan Auctioneer, making it hard to remove for one turn, which gave the rogue player option to cast a huge number of spells and draw most of his deck on the following turn.
Conceal is also commonly used to protect a gigantic Edwin VanCleef after it has been played, making sure the minion gets at least one attack before removal.
|Gadgetzan Auctioneer||Rare||Neutral||Minion||General||6||4||4||Whenever you cast a spell, draw a card.|
|Edwin VanCleef||Legendary||Rogue||Minion||General||3||2||2||Combo: Gain +2/+2 for each card played earlier this turn.|
|Preparation||Epic||Rogue||Spell||General||0||The next spell you cast this turn costs (3) less.|