What is the range of Irisalis's clone beams?

No distance figure exists for the clone beams, so treat the clones as an anchor you fight beside. Each clone stays where it was left and lasts 30 seconds. If you drift away from it during that window, its beam no longer reaches your target and the damage is simply lost.

This matters most for Floral Descent. The phantom slams the ground for area damage and leaves one clone behind on that spot. If you want that clone to contribute, keep the fight close to where you cast it rather than chasing a target across the field.

Irisalis's dash covers a lot of ground, which makes it good for evasion and just as good at carrying you out of beam range. A long dash away from your clones can turn a clean dodge into a wasted clone.

When the clones actually fire

The clones attack in a burst when you trigger them. Blossom Swarm makes every active clone fire floral rays at the target when you cast Blossom Rain Vortex or finish a basic attack combo. Bloom Cluster also makes all active Iris Clones fire a Floral Gleam Beam at the target. Its trigger is unsettled: it is described both as your dash and as landing the final hit of a basic combo or casting Whirling Blossom Rain.

Either way, check your position at the moment of the trigger. Finish the combo or cast the skill while you are still near your clones, then reposition.

Not settled: The game gives no exact distance for the beams, so the cutoff point has to be learned by feel. If Bloom Cluster is triggered by the dash, the dash that fires the beams can also take you out of range of them.