The problem is, no we do *not* know how powerful an Archdruid is supposed to be.

The last time anything was said about the relative strength of an Archdruid was back in 2nd Edition. And that said that every regional has three archdruids. And that they where chosen through a duel, meaning htey are the strongest of that circle. (Added via Edit)
I actually struggle to find much info about on how an archdruid is chosen. He could just be the wisest of them or a natural leader or something like that. There is actually not a single rule that demands a powerlevel in the 3rd, 4th or 5th edition, aside from the fact that the cornerstone feat of druids is called "Archdruid".

Bottom line, as long as Halsin is the strongest in the druid circle I fail to see a reason why he can't be an Archdruid.
On top of that, there are reasons why a powerful character may be helpless or even refuse to escape.

He could be contemplate the teaching of Eldath. He could worry that escaping would increase the number of Goblin attacks on the grove. He may see this as a chance to test the other druids to find a solution on their own.

He could also be drained by his duties. Since information about archdruids is rather sparse, he could need to meditate daily and expend a bunch of spellslots to heal a wound in the land.

He could also be level 18 and just get overpowered by a horde of goblins. A single character can get overrun. He could also be tired, because they don't give him enough too eat and drink and interrupt all forms of meditation, praying or rest to prevent him from regaining his spells and shapeshifting.

Bottom line: There is no indication that he should be able to crush the goblins and easily escape just because he hasthe rank of Archdruid.

Last edited by Fox of Embers; 12/08/21 03:30 PM. Reason: remembered something