Onslaught league

"The attack, cast and movement speed of monsters of Wraeclast has been increased. Like a lighter version of the Turbo race events, lasting for four months."

- Description on the official Path of Exile website

The Onslaught challenge league was a four month hardcore league that was aimed at players who are looking for more challenging gameplay. In this league the attack, cast and movement speed of monsters was increased. In this regard it had been characterized as "a lighter version of the Turbo race".

It was announced on May 31, 2013, along with the Anarchy league and started on June 7, 2013. It ran until October 7, 2013. At the end of the league surviving characters and stashes were moved to Hardcore league. As with regular Hardcore, characters that die during the four months were moved to Standard immediately.

Modifiers
All areas had

Items
Onslaught had six exclusive base item types (all shared with Anarchy) and four exclusive uniques (two of which are shared with Anarchy). Two base types, and, and the unique  were disabled in both Onslaught and Anarchy. After onslaught ended, the new base items were implemented in the regular leagues as well. The exclusive unique items did not, but may return in the future.

Exclusive base item types
The following item types were introduced exclusive to Anarchy and Onslaught. Following the end of the leagues, these base types became available to drop in standard and hardcore permanent leagues.

Exclusive uniques
The following uniques were shared between Onslaught and Anarchy.

These two uniques are/were specific to Onslaught league. It may affected by version 3.14.0 change, which added some league-specific items to the core loot table.