same as i wrote on other post;
well i had big issues here on walker on master mode, chapter 1. first i tried avoiding some adds on the way to the shrine. cant do that, cause if you sneak past some they basically teleport after you engage some other adds later, so no way to survive like that. kill in order, smaller groups, try breaking rocket launchers.
as for the boss, avoid red AoE. when he summons rocket adds, immediately search for them and throw gravity or rocket. kill asap, every time. i managed it like that in first try.
hope this helps