History of Chained Up

Chained Up is a Warlock triumph: as a Stormcaller, defeat targets with Chain Lightning.

How to complete

• Use the Stormcaller subclass and kill with the Chain Lightning melee. Per a Bungie forum reply, only the top-tree Warlock melee grants Chain Lightning, so grenades, the super and other melees will not progress it.
• Forum players reported progress as very slow or seemingly broken (roughly one counted kill per 100 enemies killed in one report). Advice given there was to farm in rooms with many Thrall using the Claws of Ahamkara and Monte Carlo; this is player advice, not confirmed by Bungie.
• Chain Lightning kills do not seem to count in every activity; one report tried it in Escalation Protocol without progress.

Unconfirmed

The seal or reward this belongs to was not found in the sources I opened.