I wouldnt call that a offtank build, but i tried it, and its quite nice..:)

The Phanton Dancer is almost entirely for critical damage and movement speed. The goal was to get that as early in the build as possible, as it helps with the lifesteal.

Shurelya's is actually kind of an afterthought - and I'll make a second tab to explain, than's for pointing it out. Philosopher's Stone with it's gold bonus was the goal - but you're quite right, Heart of Gold early game, and Randuin's Omen later on, might actually be a better move. I'll give it a shot and see what happens.

Magic resist is almost a non-issue in most of the games I've played lately - aside from the odd Xerath and Ahri, most of the champs I've seen the past month are heavy AD, or AS. As such, I've geared for Riven's CC and chase capabilities rather than trying to address everything. But I'll give Force of Nature a shot as well, see what happens.

Thanks for the comment! Really appreciated! I'll update soon as I've tried out the different array.

Nice build, I see that you're going for a Riven build that does a ton of damage. The use of Shurelya can definitely help you catch up to fleeing enemies. But there are a few things that bother me...you have no magic resist in this build. Maybe try a Force of Nature or something. Also, Phantom Dancers may not be the perfect choice for riven, although that's just a matter of preference.

If you're worried about riven being squishy early game,try getting a heart if gold for the hp, it even helps your income seeing as you have a very expensive build.

Overall a detailed and good guide with thorough explanations. +1