I haven't altered hammer chances. (So yes, a matter of luck in this case)
I haven't altered combat option odds in the Outerworld, however, the odds of getting skulls increases the further you progress in the Outerworld (Up to a certain limit, but this has been in place for a long time)
I'm back at the very early stages. I started from level 1 with a noob team to try and build up some of the low level characters in the hope that some of the high level characters would appear in Expansion. No luck yet.
It is fine battling rather than solving puzzles, but if nothing has changed then it's just perception or luck. No worries. Good to know that nothing has actually changed.