Ancient Watcher is a Neutral class Minion that can't attack. If silenced, the Ancient Watcher can attack, and therefore decks that run with multiple silence options can benefit from this card's low cost and high stats. Decks that have the ability to give a unit taunt, also can use the Ancient Watcher effectively.
Cards that can't attack are usually not that common, as they require another card to be of any use. It can either be given taunt by a card like Defender of Argus or Mark of the Wild, or it can simply be Silenced to remove its effect.
It can be very powerful in a warlock deck that contains a Void Terror, as it can basically give you a 7/8 minion on turn three. Combine that again with a Flame Imp and you have a turn three 10/10 demon on the field.
|Defender of Argus||Rare||Neutral||Minion||General||4||2||3||Battlecry: Give adjacent minions +1/+1 and Taunt.|
|Sunfury Protector||Rare||Neutral||Minion||General||2||2||3||Battlecry:Give adjacent minions Taunt.|
|Ironbeak Owl||Common||Neutral||Minion||Beast||2||2||1||Battlecry:Silence a minion.|
|Spellbreaker||Common||Neutral||Minion||General||4||4||3||Battlecry:Silence a minion.|
|Keeper of the Grove||Rare||Druid||Minion||General||4||2||4||Choose One - Deal 2 damage; or Silence a minion.|
|Silence||Common||Priest||Spell||General||0||Silence a minion.|
|Mark of the Wild||Free||Druid||Spell||General||2||Give a minion Taunt and +2/+2. (+2 Attack/ +2 Health)|
|Mark of Nature||Common||Druid||Spell||General||3||Choose One - Give a minion +4 Attack; or +4 Health and Taunt.|
|Shadowflame||Rare||Warlock||Spell||General||4||Destroy a friendly minion and deal its Attack damage to all enemy minions.|
|Wailing Soul||Rare||Neutral||Minion||Naxxramas||4||3||5||Battlecry: Silence your other minions.|
This card's art depicts one of the numerous living giant statues in the Tol'vir zone of Uldum. Creatures like the one on the card are seen in numerous pyramids including the dungeon Halls of Origination. The card also shows a desert and a Tol'vir statue below the actual Ancient Watcher. The ancient watchers encountered are also either malfunctioning or pretending to be inactive, until you come close enough for them to attack you. 
- "Ancient Watcher - Hearthstone: Heroes of Warcraft Wiki" on Gamepedia. Retrieved 17-03-2016.