>>96323353
You could also just, not run a Siege breaker. Or even just run 1 unit of 4 instead of 2 units of 2.
The real power of phosphex isnt the damage (though it is nice) its the fact that they're panic 3 So everyone immediately shits themselves the moment the bombs come down and are almost completely useless for a turn afterwards.
Odds of an MEQ not immediately routing from a touch of phosphex is 28%. If its not a cataphractii command squad or lead by a Chaplain its gonna run away.