Blue is on offense, 2 players start as handlers downfield, the other five line up vertically (hence the name) this is the starting point for the offense. Red is on defense forcing flick, so the left is the break side and the right is the open side. it is important for the stack to be the right distance away from the person with the disc (~10 yds or less)in order to not crowd the handlers, but it cant be too far either otherwise deep cuts wont work. it is also important for the people in the stack to be spaced out enough to not bump into or slow eachother down, but the stack also shoudn't be too long.
Cuts will come from the back of the stack, you will start your cut aiming at one of the corners of the field, DO NOT cut horizontally or straight at the handler (it is okay to make straight deep cuts sometimes). in this slide number 7 has chosen to make an under cut to the open side. one of the disadvantages of vert stack is that once you have committed to cutting under on one side it is hard to change sides without commiting a pick.
if you make an under cut and are looked off by the handler you should clear (still watch for the disc and keep running) back into the stack, usually right behind the person in front. in this case number 7 was looked off and cleared into the stack behind number 3, the rest of the stack moves up. slightly before number 7 has finished their cut, number 6 will be next and ready to make their cut. (if making a deep cut clear on the break side if possible)
if two cuts have been looked off it is time for the thrower to look to the other handlers for a dump. the handlers are very important in vert stack since it is easy to poach and a good way to counteract that is to keep the disc moving. one handler should be positioned on the open side and slightly behind them unless the disc is on that sideline (their defender may be poaching the throwing lane so they might move upfeild and to the sideline to move the defender). the other handler is the front of the stack.
the first option will be a wrap cut from number 2, going around the back of the handler to get the disc on the break side, the front of the stack will then be ready to make a continuation cut. defenders 1 and 2 may call a switch and swap who they're defending to stop the continuation. if number 2's defender is following him very closely on the wrap cut, it may be viable to change directions and come up very close on the open side of the handler to get the disc. If both cuts from number 2 are looked off and they clear it is the front of the stacks job to make a cut and try to get the disc (mostly open side under although deep cuts are sometimes viable).
if the disc is on the sideline, the stack will set up at an angle to open up the lane and make it easier to cut. this only happens when first setting up (at the start of a point or after a turnover) and is not neccessary to do in the middle of play since the disc is moving around a lot . if the disc is on the open side sideline number 1 will have to stand on the break side, otherwise they would be out of bounds (and if on the other sideline the wrap cut isn't always available. the defense would put on a fire defense here (other side would be ice) so the cuts when the disc is on the sidelines are exactly like in sideline drill. if all the downfield cutters are looked off the thrower will look to their dump. if that cut is looked off it is once again the front of the stacks job to make a cut.
the endzone play for vert stack is the same as for how stack and is very similar to how the offense normally works, except that cuts now come from the front instead of the back. spacing is especially hard in endzone since there is little room, and the back of the stack will sometimes have to stand out of bounds by a little. when switching to endzone someone will be designated the "iso" and will be given extra space to cut. the iso will be ~10yds from the handlers and the rest of the stack will be ~5-10yds behind them. if the disc is on the sideline someone will call "sideline" which means that the first look will be to the dump **the stack should not be angled in endzone**. the iso will wait until the dump has made their cut, either going for the continuation pass if the throw is made, or filling in if it is looked off. if the disc starts in the middle then the iso can make any cut to get open, make sure to keep running and always be ready to be thrown to even when clearing. the next cutter will then go once the iso is finished cutting. if your defender is poaching off of you make sure to call it, this is how a lot of over the top throws happen but remember that they are risky, especially in wind and other options should be considered first. a note is that the defense may play a little off to the open side so as not to get broken there easily.