If you want to spec into HG, might as well max it out... Build
I don't know if you have Raider, but if you do then this is a really good build. Raider and HG are both deadly in close range and DI has the speed to get close.
Recharge speed on RM isn't necessary as you can use cloak to override it's cooldown by casting the mine from cloak.
HG can be skipped if going for a sniper build - Build
Not sure what level your valiant is at, but you can use any sniper rifle. I like Valiant the most on him.
These are the builds I use. Depending on what equipment/gear you have at your disposal, they may vary. In the first build, grenade capacity V can be replaced with shock trooper if you don't have the former. AP, disruptor and incendiary are viable alternatives for both builds but I like warp the most.