So i buy Dagn his shop. It's built and I go to his town prepared to get the lawbringer quest line. Only I get an quest called onslaught instead and can't find the pieces that are supposedly in merchant stalls.

Did Laawbring/onslaught quest get comingled somehow as bug or is there been a change?

Would of used the bug report but I am unsure if it is a bug or a change.

Thanks

I have the very same problem. Got the Onslaught quest, pieces nowhere to be found. Literally went through the entire map.

The pieces of Onslaught are available as follows:
1. Cuirass: available from Oleg
2. Jambarts: sold by Hassuf in your capital
3. Gauntlets: sold by Dumra in the Secluded Lodge

If you're not seeing these, ensure you're not filtering vendor inventory and/or check all the filters. In the event you're convinced they're not there, file a bug report via the F11 hotkey.