Notes

[Rakta Dark Dagger] has a very low crit chance and crit multiplier.
I don't think [Blood Rush] makes lots of difference in this build.

Why Gas Build?

if the enemy has radiation and gas proc, the shield heal will be active each seconds. which is really good for your warframe survivability.

Too Much Forma?

you can change [Primed Fury] with [Berserker Fury] if you wanted, and reduce 1 forma, by using vazarin polarity on [Healing Return]. I think [Primed Fury] is more reliable though.

How to deal a better damage?

I recommend use this build with [Saryn], because she deals lots of damage in melee (with her 3rd ability), but a little bit squishy.
Therefore, we can increase the damage with her 1st and 3rd ability.
Don't forget deal lots of status with [Cedo] or [Epitaph]