A good build, but the threat meter is Abit wrong. Your underestimating some of the heroes. Taka can hide and ambush you anytime, which means you need scout traps or flare guns. While in team fights, he can target you first, dashing to you immediately. You can counter with the slow but it won't be enough unless you get FrostBurn. Which then you might be able to kill him before he gets you.
Koskha is the same, so many gap closing skills, the passive especially deadly. If she locks you with her ultimate your toast. Dancing in and out of SAW to kill him? Well it won't be that easy because he have a roadie run that deals tons of damage regardless he builds Crystal. After that if eh have something like thornado trigger, Bonesaw etc etc you will die. Adagio is not as easy as you think because he have high sustain with his heal. Together wth clockwork you won't be able to solo him.

As for petal I suggest hiding in a bush to use your Ultimate then go in. Hopefully it will kill one or two pets due to the AOE burn.