The Dummy Reversal

First, a few mathematical verities. If you have five trump in the closed hand, three in dummy and lead that suit five times, you have five winners in the suit. (I am presupposting all top trump to avoid a lot of qualifications.) If you ruff twice in the long hand and then lead trump 3 times, you still have only five winners. But if you ruff once in the short hand and then run your long trump, you have six trump winners. But there is another way of coming up with six trump winners while drawing trump, and that is to ruff three times in the long hand and draw trump with the short, or at least draw the last round when the long hand's trump have been exhausted.
This is called a dummy reversal, a reversal of the more common practice of regarding the closed hand as the master, from which losers are counted, and with which declarer draws the opposition's trump. You can't do it on every 5-3 hand, of course. You're going to need some high trump in dummy, a goodly supply of entries to dummy to get those ruffs and finally to draw the last round of trump, and not least, the distribution that will allow the long hand to get enough ruffs. But when circumstances are favorable, it will offer a way of snapping up an extra trick that inattentive declarers are not finding.
I don't believe I've ever seen a discussion of the dummy reversal without a 5-3 trump holding, but I'm using the term a little more broadly to include all hands, including one where the trump are 4-4, where it would be easier to count losers, or more profitable, to treat the open hand as the master. I want to cover such hands because there are people, including a number with a fondness for transfer bids, who simply cannot think of the open hand as the master. So even if by their bidding methods, the closed hand holds two trump, the open hand 5, they will immediately set about getting ruffs in dummy, the very thing they shouldn't want to do.
To be sure, there are bound to be times when you have a double dummy reversal in such circumstances. Dummy has five trump, the closed hand 3 and the hand plays best by ruffing three times in the long holding, preserving the 3-card holding for drawing trump. But that's going to be rare -- far, far rarer than the times people butcher a hand by being unable to think of the open hand as master.

I have taken six dummy reversals from my book Sixty Hands and may add a few more as time goes on.