If you want to solo Baron by a maximum of 25 minutes and obliterate entire teams whether they are tanky or squishy, the classic Cowsep and carry build is for you. Keep in mind I am not claiming to be a jungle god, but you can't really go wrong with this build. BTW, I have done a blurb for every jungler in the game. You can beat 90% of them if you were to play perfectly, but some of these guys can be really tough. Project Yi skin recommended.

Pros:

Really good for shredding tanks, and can also 3 shot squishies if you are stacked up.
Can solo Baron reliably at the 23-25 minute mark depending on the game.
Can easily split push and shred turrets if you need to.
This is Cowsep's go to build when he isn't playing Crit Yi. (which is kinda ballsy)
Best teamfighting build out there for Yi when you utilize it correctly.
Can be quite tanky late game.
Does high magic, physical, true and max health damage.

Cons:

Doesn't have much lifesteal.
Has slower kill times than the Crit build.
Can be shut down really easily by CC as you need to stack up Guinsoo's to get full effect.
Extremely expensive build, so if your games are short then probably don't build these items.
Slow to hit power spike compared to other builds.
Because of commitment to three really expensive items, you can't really fit in that QSS or hexdrinker till after even if you need them.

I'm not going to make a full Master Yi written guide as the point of this guide is the build. This is my first guide and I hope to make more in the future! Please upvote if you fine this helpful and please comment and downvote if you have any criticism. Thanks.