With [Blood Rush], Gladiator Set and Both Umbra mods you get into Red Crit territory (251% flat Crit chance with no further Gladiator Mods, with the full set you get up to 339%).

Alternatives:

• Organ Shatter instead of Amalgam Organ Shatter (A little bit more damage for those who do not want to throw the thing)
• Get Status into the build with Weepings Wounds for Gladiator Vice (You could combine that with Condition Overload)
• Berserker for Quickening (It ramps up to 12x combo-counter faster with Quickening, but Berserker is a little faster when a fully charged)

With the Deconstructor you can get the Gladiator-Set Bonus to max, without using slots on the [Xoris]. ;)