Welcome! You've chosen well - Call of Cthulhu is a fantastic game.
You've got that correct. Starting with the active player and alternating with the non-active player to take one action each, players can take as many actions as they want during Operations (and every other phase where permitted, as per the Detailed Turn Sequence diagram in the rules), and therefore can drain as many of their domains as they need to take each of those actions.
* You may only place one resource under a single domain during the Resource phase, but you can spend as many of your resources as you choose in each phase where actions are permitted, by draining an available domain per action if required.
* You can only drain one domain to pay the resource cost of one Character, Support, Event or Conspiracy that you want to play, or of a card triggered effect (like Action, Response or Disrupt) with a resource cost that you wish to trigger - i.e. you can't pool the resources of more than one domain, and any excess resource value where you may have overspent are lost (e.g. draining a domain with 3 resources to play a 2 cost card, overspending by 1 resource).
* To pay for a 0 cost card, you don't need to drain a domain, nor does it matter if all your domains are drained - although you may still have to meet other play requirements of that card like Steadfast.
* Only the active player can play Character, Support or Conspiracy cards during the Operations phase, while both active and non-active players can play Events or use Character triggered effects.
* Playing a card, as well as using triggered effects (like Action, Response, and Disrupt) is considered to be taking a player action; however Forced Response triggered effects are considered a game effect and not a player action, because they have to be triggered when it says and the player has no choice in the matter.
Edited by jasonconlon, 30 March 2014 - 06:05 PM.