With invis and smoke, you shouldn't be getting hit at all.
The problem is there. You're assuming:
- They are always alone and don't survive your first combo
- They don't have dust/ward/track/amplify etc
- They don't have enough burst damage to kill you in half a second with your +30% damage taken.
Riki is pure paper. Adding 30% more paperness because most pubs usually honor the three conditions above may not be the best choice.
Also, for Vlad users: It announces you're there because of the aura. You may as well have a Leoric in your team or something.
One last advice: DON'T BUY ETHERAL BLADE, except if your team is full of nukers(not a common scenario)... Iv'e seen like 30 rikimaru with this item in the last month...