Watchman from a Distant Land's Journal

According to the East Watcher's Journal, you can summon a Mutant Wandering Giant when used within its designated spawn location.
※ Another Summon Scroll can't be used while a boss is present.
A party cannot be formed while summoning a boss.
If you fail to defeat the boss in 30 min, it will disappear. The boss will also vanish if not engaged in combat for a span of 2 min at any point after being summoned.
There's no penalty for death while fighting the boss.

※ Available from Lv. 56.