I have a nin/nin/soul I built for PvP. Long story short, don't. There are better primaries to pair with /ninjutsu.
For PvE, having divine avalanche definitely helps survivability. It also is a beautiful set, and with good recharge, has an effective attack chain. However, it is a late bloomer, and I had to respec once I had the better attacks. It's a fun set for PvE.
For PvP, outside of fiteclub, Divine Avalanche really isn't going to help you at all - and this was my mistake in designing my build. I built mine to double-stack DA. As players move around a lot more in PvP, it is hard to reliably rely on Divine Avalanche - especially when you want to use your harder hitting attacks anyway. You'll find that outside of Retsu, you are incredibly squishy.
It can be that I don't have patience for PvP on my nin/nin, but it just seems like other primaries perform better when it comes to PvP.
I'm making a Nin/Nin, will that be viable for both PvE and PvP? And what can I expect to get out of my powersets?
Pow! Kablooey! Freem! Whiff! Bop! Zow!