Elder Baldur

Hunter's Journal
Elder Baldurs are enemies in Hollow Knight. They are adult Baldurs with thick armour plating who block pathways. The ones guarding Ancestral Mound and the entrance to Greenpath are not optional and must be defeated in order to progress through the game.

Behaviour and Tactics
Remains stationary, taking no knockback. It has three attack moves:
 * Summon Baldur: It will occasionally spawn a Baldur
 * Spit Venom: It occasionally spits a blob of venom that will linger on the ground for a small amount of time
 * Shell Curl: When approached, it will curl into a ball that cannot be damaged.

The only way to kill it is by using Vengeful Spirit or Shade Soul. Kill the Baldurs it spawns to gather SOUL to cast the spell and shoot it when it's not cowering.

One encounter on the boundary of Greenpath and the Howling Cliffs involves fighting two of them at once. Do not stand in the middle of the room, approach one Elder Baldur until it rolls into a ball and stay there until the other one has died.

Location
There are four of them throughout the game:
 * One in Ancestral Mound
 * Another guarding the entrance to Greenpath
 * Two in the Howling Cliffs, inside a "trap chest".

Trivia

 * If the Elder Baldur located at the entrance of Greenpath is encountered without Vengeful Spirit, it will not spawn Baldurs and instead, only spit venom and curl into a ball when approached.
 * They are referred to as "blocker" in the game files.
 * Baldurs summoned by the Elder Baldur do not drop any Geo.