Jason of Pherae was a thessalian leader that, for the first time in a long time, managed to unify Thessaly under one rough rule, ending taking the title of
tageuo/
tagos (roughly tyrant or archon) of Thessaly.
He seems to have been equally skilled in politics (more than his son) and in military (being considered one of the first to use hemithorakion before it got more widespread).
His sudden rise was as much suddenly stopped by his assassination in -370, but he seems to be almost a prior exemple of what Philipp of Macedon achieved eventually : political and military build-up, then interventionism.
It's not really sure how much he planned to intervene in Hellade proper, altough he had a real influence on central Hellade, but he's said to have planned expeditions against Achaemeids.
Your mission, should you choose to accept it, is to find a way for Jason and/or his successors to gain a lasting influence and domination over Greece (at least Hellade). It can have a different form than Macedonian obtained and maintained it, but Thessalians must have a clear hegemony over the various poleis and ethnic states.
What would be the changes brought by such Thessalian hgemony?
Bonus point if Thessaly can have an overlordship over Macedonia, and double for expeditions against Persians.