The Q node in Martyr’s Battleground. The node only exists while the way in from Ukgoth is open.
Where it is
Martyr’s Battleground. The marked map is on the location page: Martyr’s Battleground.
Getting it
Solved at Ukgoth, not here. Place all five tokens inside the stone circle there, then cast Martyr’s Battleground in that room — or Truce, while player killing is switched off. A portal to the Battleground opens and the node switches on with it. There is a portal out of the Battleground to the Hermit’s Hut if you need the short way home. This node can be attacked by the Xeochicatl, but it is never the one picked at random.
Melding
Stand within three squares of the node and use it. The bond raises your maximum mana by three points plus one for every ten points of Mysticism above five, so between three and eight depending on how mystical you are. You can bond with each node once, and the game will list the ones you hold if you ask.
This node can be drained by the Xeochicatl. See Nodes for what happens when one is attacked.