How do you unlock heroic dungeons in Wotlk?

Every dungeon becomes available on heroic mode once you reach level 80.

Numbers indicate the minimum level to enter, if known; and the recommended level range (in parentheses).
The recommended level range is also the range required to be able to be summoned via the summoning stone.

How do you enter a heroic dungeon in TBC?

Heroic dungeons are in a unique state in The Burning Crusade where they will require a key as a type of attunement before the player is able to enter this harder difficulty. Basically, players will need to earn Revered reputation with the factions associated with that dungeon.

How do you unlock heroic dungeons?

In order to enter heroic dungeons in Battle for Azeroth, your character must be level 50, meet a certain item level requirement, and have unlocked the Heart of Azeroth. If they do not meet any of these requirements, they will not be able to queue using the dungeon finder for heroic dungeons.

How often can you run heroic dungeons?

once a day
Heroic mode dungeons are on a lockout timer much like raids, and can only be run once a day per character. Each dungeon is on an independent timer, however, so a character could run as many as 15 heroic mode instances per day.

Can you enter heroics before 70?

Nope. You need to be 70 to get into a heroic BC dungeon.

How do you get heroic keys in TBC?

In TBC you will have to improve your reputation to Revered with 5 of them to unlock all the Heroic dungeons. The good news is that with further patches the required reputation will be reduced to Honored.