Based on the latest ruling, Icathian Rain no longer creates 6 reflexive triggers, so what happen now if there is only 1 enemy unit with Deflect 1 on the board, and I have casted the Icathain Rain, but refuse to pay 6 extra power as the deflect cost? Does the spell still go onto the chain?

Wrong ruling on reflexive triggers and Ichatian Rain.

That premise isn't correct — under the current rules Icathian Rain still creates six separate damage instances, each with its own target choice. The card errata changed the wording from "Do this 6 times" to six "Deal 2 to a unit." lines. During finalization of the spell, targets have to be chosen for each damage instance. So if there is only 1 available target, and that target has deflect 1, you will have to pay 6 power. As for declining the deflect cost, Ichatian Rain is a spell, you are not allowed to decline a mandatory cost for a spell. If you cannot pay the mandatory deflect cost, it is an illegal play. The spell is never considered to have been played and is returned to hand.