There are a number of variations of this drill, and lots of names for it. Blending the drill into one's personal skiing is easy because the drill is almost invisible in its more subtle variations (thus the name "phantom"), and because doing the "drill" as actual skiing is sometimes good form.
I'll list a bunch of variations. Let's see how sharp my memory is - it's my bedtime but this is too much fun to leave until morning.
Variation #1. Lift the tail of the new (soon to be) inside ski. This is the ski that's downhill as you travel across the trail. Make sure the tip of that ski stays on the snow as you lift its tail. It doesn't have to lift much - an inch or so is good enough. The movement may be invisible to others.
Do this as the old turn is about to end. In other words, do it while that old turn is still happening but
almost done. Do not start the new turn first then try to lift the tail. The reason is that the new inside ski tail lift will start the turn for you, without you having to do the other things you do to start a turn. It's like magic.
This simple move, tail up while tip stays down, will start the new turn all by itself if you do it early enough, before starting the new turn your normal way. You don't have to do anything else. Keep that tail lifted until it's time to lift the other one.
----Benefits of doing this drill variation:
1. It keeps you out of the back seat.
It's almost impossible to lift this new inside ski's tail (with the tip staying on the snow) while skiing in the back seat. This drill is a good self-diagnosis exercise to see if you are skiing backseat. If you can't get the tail to come up, or if you can't keep the tip down as you lift the tail, you are in the back seat. You need to bend your ankles forward more so your shins come up from the skis at a forward angle, not vertical, and contact the tongue. Just bending forward at the ankle will do this. Do not bendzeknees to get the tongue-shin contact; just bend the ankle forward. If this doesn't enable you to do this tail lift, then you probably also need to stand up taller along with the ankle-bend. These two should get your body more forward over the skis so that you can do this drill.
2. It automatically transfers all your weight to the new outside ski.
The tail-lifted new (soon to be) inside ski is the downhill ski if you do it early enough. Early enough means while the old turn is ending, before you do anything to start the new turn. Once lifted, all your weight transfers to the new outside ski (uphill ski). This weight transfer is essential for starting almost all ski turns. You won't need to do anything of the usual things you do to get that turn started if you can lift that tail before you start the new turn.
3. It tips the skis onto their new edges.
When you lift that downhill ski's tail, your uphill ski will tip onto its new edge and start the turn. Edging of the new outside ski will start the turn downhill and then across the hill. Rotating the skis won't be needed to get them to point in the new direction. (You won't be carving so these will be slow speed turns.)
4. It eliminates leaning-in & also having too much weight on the inside ski.
When you continue to hold that inside tail up (and tip on snow) through the whole turn, you can't lean in because you'd fall down. The inside ski will not be firmly planted on the snow from tip to tail, so it can't support your upper body's weight.
5. It begins the process of learning to make advanced turns.
Using edging to shape a turn is an advanced skill. Doing the tail-lift, if you do it before you start the new turn, is a great way to begin learning to use the ski's self-turning function that is built into its design.
It's a difficult drill at first for most adult learners. Many have difficulty keeping the tip on the snow, and in my experience most cannot convince their downhill leg to lift that ski's tail. So they end up lifting it just a little once the turn is going. That's ok because they can work on lifting it earlier and earlier. This can be learned.
The new inside ski tail-lift is worth pursuing because the magic moment when a skier feels the ski make the turn all by itself is amazing.
AJM said it was like a magic bullet!
I'm nodding off so the other variations will need to wait for another time.