Ok, this is pretty seriously open ended, so I'd love to get some feedback on how you might maximize this option to create some horrific chain of effects. I want to get the text as tight as possible, so please, be evil.
NEW BASIC COMBAT FEATS
Warriors throughout history and literature have signature attacks earned through years of practice or the hard lessons the battlefield. Now you have one too.
Benefit: To create a Combo you choose two different tricks you know; one to be the opening trick and the other to be the first link in the combo. Opening tricks must be chosen from tricks requiring a half action check, a full action check, a save, a defensive reaction like parry, or a total defense trick that creates a check. Linked tricks must require a free action check, a half action check, or a full action check. If you choose a Spellcasting trick, it must be associated with a single specific spell when used in this combo. Once you have started building a combo, each time you level you may spend a proficiency to add an additional link to the combo. A combo may never include the same trick more than once.
Once per round when you have the opportunity to make a check as part of an opening trick, you may set aside your largest action die before rolling to declare you are starting a combo. If the combo has more than 1 link you choose in advance exactly how many links you are going to attempt (i.e. if you have a 4 link combo you don’t have to attempt the entire combo on every occasion). If you succeed on the opening trick, you may immediately perform the next trick in the combo as a free action. If a linked trick succeeds, you may then take the next linked trick as a free action until you either fail to perform a linked trick or the declared combo is complete.
Once a combo has started you may not perform any other checks until it has completed or failed. You may not apply additional tricks to your linked actions. If a linked trick normally requires a full action to perform, all checks associated with that trick suffer a –5 penalty. If you take and succeed on every action in the combo the action die set aside is returned to you, otherwise it is discarded.
Special: You may take this feat more than once, choosing a different pair of tricks each time to create a new combo.
Example: The bladesmaster Seska has the two link “Mix-up (feint) into bury the blade into shove” combo. On her initiative count, before using her mix-up trick she declares she will be attempting the full combo. She sets aside her largest action die and then rolls her feint action. If that succeeds, she immediately makes an attack with the bury the blade trick. If that attack succeeds (even if she doesn’t roll 4 over the target’s defense to gain the additional keen benefit) she then makes another attack with the shove trick. If the shove succeeds she gets her action die back. If any of those three checks fail, the combo ends at that point and she discards the action die.