Aerlinthe Node Pyramid
From the Tainted Ley Line Nodes quest introduced in Shattered Lines.
Located at 84.1N 44.1E on the south beach of the west side of Aerlinthe Island. Either run around the harbor, around the island perimeter beach, or use Coral Tunnels to get across the harbor.
The pyramid's light is strengthening, but there will be a long way to go before it is restored. It has not yet reached half strength.
Search for Blighted Pyreal Golems on the north side of Aerlinthe Island, they drop Blighted Mana Crystals. Give their trophies to the Node, see A Field Guide to Tainted Nodes for details.
Updated during the Seeds of Corruption event, there are now stone Gateways on the pyramids that will transport you to a Blight Lord's Lair when given 20 Blighted Mana Crystals.
You allow Halaetan Gatestone to examine your Blighted Mana Crystal.
You hold the Blighted Mana Shard against the gatestone to no effect. You get the sensation that simply trying to use the gatestone with at least 20 Blighted Mana Shards in your pack will activate its powers.