Rule 740.4.a.2
For triggered abilities, costs within instructions that appear in the first part of the trigger effect are paid on finalization of the triggered ability. In order to place the triggered ability on the chain, the cost must be paid.
Loading Arbiter…
For triggered abilities, costs within instructions that appear in the first part of the trigger effect are paid on finalization of the triggered ability. In order to place the triggered ability on the chain, the cost must be paid.