Bet My Life! Sorcery As an additional cost to cast Bet My Life!, discard a card at random. Return target nonland permanent card from your graveyard to your hand. You lose life equal to the difference in converted mana cost between that card and the discarded card.
SilentKobold - Exhausting Ritual: A good loot effect that cleanses your entire hand (even if you don’t want all gone) for a new hand. It can also disrupt your enemies, but it always gives them card advantage by one. The flashback and damage push this card pretty hard along from being good to being great. Especially against blue decks that love those cards of theirs. They can probably be punished just that bit harder as red likes to do.
Daij_Djan - Golden Rebuke: I don’t like what this asks of you. It’s a white card (which doesn’t have the greatest card draw) that asks you to count your cards in hand for the specific moment of your opponent attacking or blocking. What this can create is people holding ALL of their cards in hand for that moment, instead of playing their cards when they should. The flashback cost is neat, though I see this card mostly played in bluewhite control where you have cards in hand, so that cost might be more situational than desired.
Flo00 - Ritual of Endless Peaks: Firstly, I don’t like the hybrid mana. It should probably just be all three colors fully seeing its effects:
G: graveyard to hand
UR: discard and deal damage equal to the converted manacost.
You might even drop U if you so wanted, but the graveyard recursion as is on a possibly 1RU card gets a no from me.
Secondly, I like the combination of damage and graveyard recursion. Having it be less powerful by restricting it with the types of the card discarded (and having to discard) while also having it be less expensive manawise than for your example Vengeful Rebirth makes it a bit more playable.
Lastly, the “any target” might be pushing it. Just using this card for that effect and throwing Emrakuls at people wouldn’t be too out there. Getting a card back from your grave at that is just extra.
ameisenmeister - Regathan Resurrection: A to-the-face Tarmogoyf, with some graveyard-to-hand action. Showing your hand, especially a big hand, will of course cost you. I like that the grabbing from the grave can really help with the damage, but you have to make the choice of whether you want to have a good card in hand or a good extra one or two points of damage to destroy that creature or planeswalker. Having it only target creatures or planeswalkers is a good limiter.
Boogymanjunior - Bloodgyre Curate: I like this effect. Repeatable Morgueburst on a stick, but with an extra cost. Gotta have creatures in hand and in graveyard. Good that it’s limited to creatures and planeswalkers instead of players, with its repeatable nature and all.
odivesco - Mauling Ambush: A rabid bite that you don’t need the creature to be on the battlefield for. Good that it costs 3 instead of 2 cmc then! In-flavor for green, but still a different way to remove for green. Having it be repeatable for the same price is a bit much though. That flashback cost should go a bit higher imo.
gamma3 - Bet My Life!: Very expensive for very little payoff. Understandable that it would cost more to do something that green normally does (put any card into hand from the grave), but both the discarding and the lifeloss make this a hefty price for something that isn’t that great.
Journey Though Nyx Instant Exile target creature or enchantment you control, then reutrn that card to the battlefield under it’s owner’s control. If it enters the battlefield as an enchantment creature, it enters with an additional +1/+1 counter on it.
Kind of disappointing that we didn't get a card of this climactic moment in Theros Beyond Death. Let's fix that.
The Spear Shatters Sorcery
This spell costs less to cast if it targets a permanent with indestructible.
Exile target artifact or enchantment. If it was legendary, create a token copy of it.
It never crossed Heliod's mind that mortals would believe that Elspeth's spear was the real one until the moment his own splintered in his grasp.
White gets to exile artifacts and enchantments, so that's in. Gods are indestructible, let's have a bonus in the form of cost reduction for targeting those. White is also the top color in "legendary matters", so how about an unusual steal-effect in white by making a token copy if it's legendary. After all, Elspeth did basically steal Heliod's spear.
There. The critical moment of Theros Beyond Death, finally in card form. I'd include a render but I couldn't find art.