Hello I recently started leveling my rogue and I’m a bit confused about the use of Vendetta in the opener. From what I’ve read online you are supposed to only use it after you are done with your initial stealth opener set up. Why is that? Do you not want the damage increase buff to affect your initial “in stealth” abilities, Rupture and covenant abilities? Since it lasts a whole 20 secs it could still empower maybe 1 or 2 Envenoms and your Vanish empowered abilities?
Thanks
Your opener is usually buffed coming right out of stealth due to talent choices (for me, Subterfuge)
Bleeds are dynamic and don’t snapshot - meaning they only receive the buff while Vendetta is active, and will go back to normal power once Vendetta drops off. Better to not waste Vendetta’s buff while getting everything set up (slice and dice and bleeds rolling)
Once you get things rolling and are ready to start with an actual rotation, you’ll use Vendetta coupled with Vanish to rebuff everything, and fit in as many Envenoms in that window as possible.
Look at it as a small ramp up time before dropping cooldowns to do big damage
Theres also the Energy regen to take in mind, youre better off using Vendetta when youre somewhere around half Energy or less, otherwise you are likely to waste it.
And that! I always forget about the 60 energy over like 3 seconds 
Reason #3
Most players will macro an on-use trinket or potion (Saltwater Potion) with Vendetta. Activating an on-use item will break stealth.
Something like this:
/cast Vendetta
/cast Blood Fury(Racial)
/use 14