Needle Knight Leda

Speak to Leda in Mohgwyn PalaceLandmark and touch the withered arm as instructed.

After defeating the Divine Beast Dancing Lion, there will be the Tower of Shadow Message letter from Leda at the top of the stairs

Receieve the Castle Cross Message, from Leda at the Castle Ensis CheckpointGrace site of grace

Optionally summon Leda to fight Rellana, Twin Moon Knight

Talk to Leda at Highroad CrossGrace Site Of Grace in Scadu AltusRegion.

Speak to Leda at the Highroad CrossGrace and choose Hornsent and Thiollier.

Speak again to Leda at the Highroad CrossGrace.

Defeat Messmer.

Within the Shadow KeepDungeon, choose from gold and red summoning signs to aid Leda and kill Hornsent

Speak again to Leda at the Highroad CrossGrace.

Get Message from Leda at Highroad CrossGrace

Progress through the main story enough to reach Enir-IlimRegion (Travel to the Church of the BudGrace in the Ancient Ruins of RauhRegion and beat the boss there).

After burning the tree beyond the church and travelling to Enir-IlimRegion, advance to the Cleansing Chamber AnteroomGrace Site Of Grace.

Fight Leda. On transport back to world, find her body as you continue climbing the tower