In a Showdown battle, no.
Why ? Because Evasion moves are banned.
This set is risky. It could work well occasionally, but fail as well.
Firstly, get rid of Fire Blast. Blissey has poor SpA stat you are better off with a move that causes a set number of damage.
If you really wanted to use this I suggest :
[email protected] Incense/Lefties
252HP/252 SpD/4 Speed or /4Def or /4SpA
Don't bother to much with her Defense or both Atk, SpA and Speed you're better of maximizing her stats she excel in. Seismic Toss over FB. Blissey doesn't have horrendous SpA but Seismic Toss is better. If you are gonna go for FB give the remaing 4 EV in SpA.