Wonderful news Marth mains! ~
Alright guys, I think you'll like this treat. I now have found a fairly reliable way to kill Meta Knight at earlier percents. I also have tested a few things you might like.
First off, the kill method. Release Grab to Dancing Blade is able to kill Meta Knight starting at 72% and up on Final Destination. Don't believe me, right? Normally, if you attempt to use Marths upwards Dancing Blade attacks, the final swing would miss Meta Knight at lower percents (BTW, in case you didn't catch that, don't use it on MK at lower percents. Use the Red/Green variations). However, at higher percents, starting at around 70ish%, MK starts to pop upwards. If MK is grabbed and released and the Dancing Blade combo starts at around 72%, MK is in perfect range for a final tipped blue swing. 72% is the lowest MK can die from if the combo starts at that percent without DI. The higher the percent, the harder it becomes to avoid due to added hitstun and the fact that you can use the combo faster to ensure the tipped hit (the lower the percent, the more it needs to be timed).
This is by far the easiest method I've found to kill MK with. Smash DI may screw with this, and DI may too, but they cannot escape the combo through regular DI, and avoiding the tip through regular DI seems rather difficult as well. I should also note that using a regular Dancing Blade combo won't work, as it won't pop MK far enough in the air to tip with it. It needs to be from a Grab Release. As for my other findings, I think they're rather useful.
Mach Tornado: First off, if you find yourself stuck in it, the best method used is to break free is to not DI at all. Leave the control stick alone. On most occasions, Marth should bounce upwards at some point. This will allow you to fast fall an Air Dodge through the rest of the Tornado. Now, if you wish to out prioritize the nado, FSmash, Dolphin Slash, Dancing Blade (risky), and Shield Breaker all work fairly well. I thought I would mention these, as MK users who like to fight at close quarters and like to stay on your *** all the time may activate it too close in order for you to use your Counter fast enough, so these will help you out.
Drill: If you are caught in this, the best method against it is to Smash DI into it. Semi Circle the control stick towards MK and if done properly, you should only recieve 1-2% damage and you will break free. Also, if spaced properly, this leads to free tipped FSmashes. This gets a little more complicated if the drill is curved upwards, but the same strategy generally follows.
Glide Attack: I have found a rather reliable counter for this in the form of Standard A. Dolphin Slash is a great alternative, but it is risky at low percents due to lag. If MK isn't pushed back far enough, he will just come back and **** you during lag. To remedy this, use the Standard A. If MK used the Glide Attack, it will clank with MK, and this gives you enough time to grab MK and start up a Grab Release set up, or FSmash/Dolphin Slash him too. If MK decides to cancel his glide and land in front of you in hopes of grabbing you from your shield, he eats a Standard A. Awesome huh?
Standard A: Most MK won't use this against Marth, but it happens, so I thought I would mention this. FSmash, DSmash, DTilt, Shield Breaker, Short Hop Counter, AND Dancing Blade all go through this. Don't attempt your aerials or FTilt if this happens, as it will be a waste of your time.