You should never use tap effects in the deployment phase, as a rule. Sure some situations may work.. but tapping Master of the Forge for example is nearly always wrong. You tap it at the end of the turn as the last thing you do before refresh. This way you are porteced form treacheries that target taped units, have a emergency blocker if a super scary mod comes out.
Well, I would agree this may be valid strategy in many a quest but surely one should not call it a rule. Of course, when there is a chance of Necromancer's Reach or the like coming off the staging, then yes. But there are many quests where there is no such scare. And then it may be much more beneficial to have an extra attachment to help you: surely Miruvor, for instance, has a better utility even as a safety device than a ready Master of the Forge.
