I think I would try to not waste any more energy on the place. But reality is I would waste energy being emotional about it for a while. Honestly there isn't shit you can do as revenge that will make up for it. Other than maybe getting a much better job.
Hah well no, but they also won't pay that last day. If you use PTO they have to pay you and might not even fire you that day because of HR rules about needing to be in person/with witnesses etc
Well technically the worst (but absolutely legal) thing you can do, from their perspective is to be very well versed in your rights for the state or province you're in. Is it a dismissal without cause? Then what severance are they offering? Did your negotiate it? Basically they'll want you to sign something and promise not to sue - in exchange to signing this they'll offer something. Negotiate that... Usually in the form of X weeks of pay per years of service at your employer, but X can vary and be negotiated. You can also negotiate a referral letter from your boss even though companies usually say "we don't make referral letters" - as part of my package negotiation you will...
I was torn up because I had to fire a switchboard operator who just couldn't make it in on time. It's one of those jobs where you have to be there when the business says it's open. She got some warnings and then within a week she was late again. I had to fire her. During the termination meeting she said "This is harder for you than it is for me."