I'm trying to come up with a good power system for my planeswalker/jumpchain slop story outline.
Basically the premise is some individuals are born with a planeswalker spark in their soul that lets them travel between different dimensions or worlds. Every world can have different rules, the most are filled with humans and have Earth-like rules some have magic some have super science some have vampires or fantasy races, etc. One concept I really want to stress is that the main character is essentially gaining power or powers from traveling and experiencing these different worlds, but I sort of want an overarching "theme" to the power. That way when he inevitably encounters "evil" planeswalkers he had interesting opponents to fight.

Essentially I like the idea of getting new powers from visiting new worlds; like visiting a desert world and getting sand powers, but having a random mix of powers from any given dimension would make the conflicts too crazy. Like imagine a hundred year old plansewalker who has mastered a hundred worlds and a thousand spells- its too much to mentally contend with. Having every one of Planeswalkers have the same power is also interesting, but maybe a little boring. What should be the overarching theme of this power system for individuals?