Can I play Icathian Rain if I can't pay for all the deflect costs when my enemy only has units with deflect?

Ruling: Yes, you can play Icathian Rain even if you cannot pay for all deflect costs. Icathian Rain does not target when cast, so you don't need to pay deflect costs upfront.

Sequence:

• Cast Icathian Rain without targeting (no deflect costs required at this point)
• Icathian Rain resolves
• Six reflexive triggers are created
• For each trigger sequentially, you choose a target and pay any necessary costs (like deflect)
• If you cannot pay the deflect cost for a trigger, that trigger won't be put on the chain

Nuances:

• You can target your own units to avoid paying deflect costs on enemy units
• If there is only one enemy unit with deflect on board, you must pay deflect for each trigger that targets it (you cannot choose to not target)
• You can play Rain even with no units on board; the triggers simply won't enter the stack without legal targets