I'd prefer a meta with as little combo as possible and also a inky focused on big creature beats. This is because combo is not fun for me to play against as you have to tune your deck to combating it. Big durdly creature aggro with huge plays that seemingly come out of nowhere feels like the most fair meta to me. That said I think decks that have unintentional combos or that have 4+ specific piece combos as more or less fine. I think control is hard to build without combo so I think at a table:
Restrictive mana cost, costs 1 less than aminatous augury, only some of the top 5 get played, Sorcery... May be okay in Aminatou but even that is pushing it.
I just retired Derevi again in order to losen up some spells and mana for Niv Reborn. Kinda feel I will mis it especially sinc eit was so good but I won almost every time with it so I kind of won't mis the "this is too op" thoughts plaguing my mind. She the only one that I have an emotional connection to and I love building and tearing apart decks so otherwise I don't have this problem too much. Maybe I have too much of a problem being unattached to my decks. :/ It will get better though as a new deck in grains itself into you.
Merfolk Skydiver's ability is very expensive is feels almost not worth it for me. Might be okay as a blocker but there are definitely better cards for that slot.
I would try running some more mana acceleration. Kiora, Behemoth Beckoner is a great and cheap card for this slot but I would recommend running between 10 and 15 cards compared to the 3 you have now.
Bribery, Acquire and other blue cards do steal. Stealing is totally a blue black specialty as the blue reads their mind and the black rips it out of them.
Ult idea for him
Emblem: "whenever an opponent casts a spell you may pay x where x is that cards converted mana cost. Gain control of that spell. If there are any targets you may choose new ones."
Bring to Light specifically says creature, instant or Sorcery. Still amazing but doesn't get Astral Slide directly, can tutor off it with idyllic or demonic.
The cards I'm thinking about for ramp, Cmc 3 or less, are the Borderposts, Kiora's Follower, and Growth Spiral.
I understand that these are not the most amazing cards but I feel like one of the most powerful things you can do after drawing a lot of cards is ramping.
I was playing a five player game and one of the guys was playing prime Speaker zegana. They turn one forest into burgeoning which results in playing five lands because of sprouting vines and someone plays a fetch. They then play Sylvan primordial turn two and everyone scoops.
I used to play staxy type cards because they are great with Derevi (mainly Winter Orb and Birthing Pod into Hokori, Dust Drinker) but after reading some discussion on here I decided to build without and so far it's going great. My deck still abuses flicker locks and such but now it all feels very vulnerable. A well placed Supreme verdict or sudden spoiling can wreck me and I am usually very soft early game. My issue now is that I think I win too much with it and since the fun I garner from playing the deck is oppressive synergies that just win the game, or else I'm playing like *****, I feel awkward when I've already won a game that night. Like, I even feel insecure playing Archaeomancer with Helm of the host (even though it's a 13+ mana synergy) ... Idk maybe that is something I shouldn't feel worried about and I should be proud of how well my deck does. :/
1 control
2/3 aggro
1/0 durdly combo
That is optimal for me.
Merfolk Skydiver's ability is very expensive is feels almost not worth it for me. Might be okay as a blocker but there are definitely better cards for that slot.
I would try running some more mana acceleration. Kiora, Behemoth Beckoner is a great and cheap card for this slot but I would recommend running between 10 and 15 cards compared to the 3 you have now.
Ult idea for him
Emblem: "whenever an opponent casts a spell you may pay x where x is that cards converted mana cost. Gain control of that spell. If there are any targets you may choose new ones."
Someone else mentioned Cyclonic Rift. I believe these too are the most flexible board wipes for whatever you may be facing.
I understand that these are not the most amazing cards but I feel like one of the most powerful things you can do after drawing a lot of cards is ramping.