Getting the tome of knowledge

[Lyverbe]

I've completed the game and wander around to complete unresolved puzzles. One of them is, according to other threads, the tome of knowledge in the Twigwood Forest. It's behind a closed gate in a small area. There's a circle made of rocks in the center of the area.

I've dig ever cell of this area, hit every tree, clicked almost anywhere, slept in the circle, dropped things in the circle, went behind the tome to see if there was any button, threw spells on the door and small fire stand... I just can't get this gate down!

[minmay]

You have to

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stand in the circle and blow the Horn of Summoning.

[Dr.Disaster]

Recall how you started the first boss fight

[komninosm]

You have to

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stand in the circle and blow the Horn of Summoning.

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Do I use the Horn ever again or can i ditch it in the Hub? What about the Rapier, do I need that ever again?

[Lyverbe]

You have to

SpoilerShow

stand in the circle and blow the Horn of Summoning.

You've got to be kidding. I didn't find this obvious at all as I had completely forgotten about the first boss. Thanks!