I'd rename blood tax to high altitude and just have fatigue start immediately.
Love the addition of more, simultaneous rulesets in Champ.
I've requested this myself previously. Even if just in Wild, where there are more sets available (in case you pull even stevens, little league, magic only and only commons and rares in the same match)
I'd be keen to see poison stacks as a ruleset.
Also a fun option would be cards which deal magic damage take double magic damage
RE: More Rule Sets, Please