See Challenge # 124.

Another approach was trying to merge the mechanics, preferably divvied up by clans.

I think I would end up with five clans. Abzan has Fateful hour, mostly for flavour reasons. Sultai has Morbid. Duh. I'm not sure about the others, I might make a werewolf clan, but that wants to be RG/b not Temur or Mardu.

I'm sure I can tie together morph and DFC somehow, but I'm not sure exactly how.

The interaction between them is wonky enough without using them in the same set. 0_o

Between which? Facedown and DFC? Oh gosh yes, I didn't mean have BOTH, I meant, the mashup set would have a mechanic which was a bit like both -- eg. no DFC, but similar cards implemented with morph, or using DFC to have a similar feel to morph. (Or possibly fixing the rules on how they work together so manifesting a DFC is fun rather than confusing, but I think that probably won't happen.)

Your use of fateful hour make me wonder: what is everyone's opinion on the mechanic?

It's very hard to make it matter, unless the set has any cards like Mischievous Poltergeist at which point it's too easy to matter. I didn't play a huge number of games with DKA, but I never saw fateful hour matter even once.

Yeah, I've literally never seen it come into effect. I know they wanted to make it feel like dire circumstances, but they should have decreased the bonuses and made it 10 life, or something.

I'm sure I've cast Gather the Townsfolk for 5 at some point. It probably didn't save me, though. Don't remember.

I do have to point out that this has a very powerful payout for being low on life. That's a good choice.