Black in Theros: Beyond Death also combines a mixture of nasty instant spells like Final Death, which exiles a creature immediately, and the delightful Eat to Extinction, which devours the opponent creature - like the rotted black giant depicted on the card
This means it's not possible to cheat creatures into play out of nowhere (which madness can do), but it also means you're granted more flexibility, because you can cast a spell for its mayhem cost at any point during the turn in which it was discarded (rather than having to choose immediately as per madness rules)
Now, we have a bit of a middle ground, and helps open up the playability of these cards a little
Ultimecia, Time Sorceress / Ultimecia, Omnipotent Rating: 3/10 Im not buying it here
The deck typically adds the Selesnya enchantress package to the 17 shrines that exist, including enchantment tutors like Idyllic Tutor to seek up key engine cards like Sanctum of All
Basically, it's a super-janky version of Splinter Twin