Forbidding Strike 2WU
Enchantment (U)
Flash
When Forbidding Strike enters the battlefield, return target creature to its owner's hand.
Creature spells cost your opponents 1 more to cast.

Spiteful Imp 1BR Creature - Imp (Uncommon) Flying, Haste, Infect Whenever Spiteful Monster deals combat damage to a player, discard a card. 1/1 I guess I'm not too big a fan of this; the downside is easy to avoid and evasive infect is concerning. It's a very obvious Voltron target! Alright, I'm in....

Cursed Cartomancer 1B
Creature — Human Shaman (R)
At the beginning of your upkeep, reveal the top card of your library. If it's a black permanent card, you may pay life equal to its converted mana cost and sacrifice Cursed Cartomancer. If you do, put that card onto the battlefield.
2/1

Plant a Viceroy 2GW
Sorcery (R)
Create a token that's a copy of target commander creature you control, except it's not legendary and it's a Dryad in addition to its types.

IIW: Noncreature Dryad stuff.

Welkinshape 2UU
Creature — Shapeshifter Bird
You may have Welkinshape enter the battlefield as a copy of another creature you control, except it has flying.
0/0

I would not put this effect on a green card since green is one of the colors that gets deathtouch on its creatures, so this runs a decent risk of self-hosing.

This card is all right imo except for the excessively long flavor text, which does not add to the card in any real way. Of course the banshee poet has an unpleasant presentation style, she's a banshee.

Thanks for the in-depth feedback! I will be using those wording changes for sure. For Sanzang, how about target nonland permanent card ? It captures planeswalkers as well as the other types white can usually regrow, which normally I'd be a little resistant to, but on a mythic I'm willing to be a lit...

I'm still working on Guashan, and here's the cycle of legendaries representing the scripture pilgrimage party. Vigilance Whenever Sansang, Seeker of Scriptures attacks, exile a card from your graveyard. When Sansang leaves the battlefield, return each card exiled by Sansang to your hand. At the begi...

Over at the custommagic Discord, we arrived at the same conclusion as spacemonaut: it makes the mechanic (as used over there, empowered) too hard to use if you can turn it on with counters.

In addition, if these are Equipment, they need an equip ability.

Nikumbha the Four-Faced 4GW
Legendary Creature — Angel Hydra (M)
Flying, vigilance
Whenever damage is dealt to Nikumbha the Four-Faced, put a +1/+1 counter on it.
For each +1/+1 counter on it, Nikumbha can block an additional creature.
4/4