Why House Krast?
I can see going mechanicum to access their relic plasma decimator and the Machine Spirit Resurgent stratagem but I kinda favor the other mech houses more. I suppose with the gallant and warglaives you had a lot of close combat.
Personally the House Raven specific stratagem is so awesome I have to try it out. 2 cp, pick a knight in the shooting faze and it rerolls all 1s- so number of shots, to hit, to wound and damage rolls of 1are rerolled.