I was thinking here. Is there a way to fuse the IB build into an Agi build?
Doesn't seem like Critical Agi is a good idea for RKs...
Crit AGI is still the best overall build when it comes to MVPs anyhow, for RK's that is. No other purpose for the build. It's fun though, but that's my opinion.
AGI is only really useful, in an IB build, for BB, in an IB + BB spam, since you can almost get 3 BB's per IB with really solid AGI (around 90+), before the 2s IB cooldown ends. Just note that due to the nature of BB, the returns are diminishing, and clearly a BB spam ignores gutterline mechanics, and it's easy to be put into a position where you're only hitting 1 enemy with BB and everything else with IB.
For this reason, some people will recommend like 50~60 AGI, maybe 40 at minimum. Unless you prefer to assure each IB+BB hits that group to assure maximum output per hit. Helps in the sense that RK's have crap for SP, and more importantly, natural SP regen, without gear boosts.
Another reason for this setup of not going for maximum AGI, and getting somewhere between 40 and 60, is IB itself. Given the damage per area of affect, where you'll get much better damage close up, and much worse further away.
It's mostly about balance and what you feel comfortable with and can handle.
Otherwise, there's also the DB + IB build, which doesn't require much AGI, except that which is needed for the animation delay on DB, about 40 AGI. Then work into a pure DB and WB build except for those rare maps and scenarios where your IB output will be higher per hit, making DB/WB+IB effective.
It really depends. I mean I'd say have some fun with it. Maybe you can make a really high ASPD going with IB and BB and make it work for you (it's better this way for MVPing, if you're going to use those two skills, as an alternative to DB).