MTGNexus

• Make sure to include a rarity.
• Your card can, flavorfully speaking, have a Theros setting or any other plane.

Cacophonous Choir: Kinda awkward wording, and the effect is almost entirely useless in a single player game. Also not really what sirens are generally about, which is luring people to their doom, not getting them to attack other people.

Tetraceph Devastator: This should probably exile itself on death, otherwise you could have them constantly recurring each other. Also R/B don't tend to use tapping a lot of creatures as a cost. But overall a fun card.

Chimeric Manticore: Lotta text that would mean absolutely nothing, since no one would tangle with this in combat unless they absolutely had to. Also not a fan of taking two creature types that players already barely understand and mashing them together to make it even less comprehensible.

Cyclops of the Forge: Not sure why it's "becomes tapped" instead of "attacks" - maybe for vehicle synergies? If so, would have preferred that to be included in the cost reduction. But otherwise very fun card.

Terror of the Strait: Not sure why it's not "Terrors of the Strait," since it seems to be capturing both, but otherwise very flavorful, perhaps to a fault, since I think players unfamiliar with the source material would be very confused.

Thyroxis, Golden Ram: Legendary flagbearer with upside if it dies. I don't think emblems should be given by non-planeswalkers, especially this easily - if your opponent is playing removal, sweepers, or ground creatures this is going to die and then you get a ton of ramp and a powerful emblem. Very unfun in limited, and to make matters worse you forgot a rarity.

1. jamblock
2. kwanyeegor-ii
3. Ink-Treader

This is far too strong I feel. Even with the "can't be sacrificed" text, its pretty easy to kill, and the reward for doing so is huge. and in the mean time, it also lightning rods opponent's spells and abilities to it. This needs to cost a lot more for what it is.

A little strong, but not overbearing. Mostly just dodges kill spells and the like.

I get that it wouldn't be quite accurate, but I really want this to be a Minotaur Snake. That aside, this is very solid card.

Mythic feels weird here. It's certainly decent, but this could perhaps be an uncommon. The last ability isn't so powerful on its own.

I'm not sure what exactly this is referencing, but it does feel like it belongs. A Creature saga is very weird. This card can grant a lot of card advantage, but it gets risky. It does allow someone who doesn't want to take the risk to get out of it at stage III at least.

Pretty powerful if it gets to stick around. Being able to repeatably send creatures back to hand is potent. Doesn't seem too overbearing considering the mana investment.

1. Subject16
2. slimytrout
3. Henlock

Ink-Treader - This does create some tension and obviously wants to be abused with Top. It does a whole lot of interesting things but the fact that it's either swingy in a way that might not be fun, or VERY good if you can manipulate your library, might be oppressive.
FoilSquared - Yes, you can't sacrifice it, but being able to deal 1 damage to this to get all those rewards feels like a quite easy way out, especially since you will easily net back more mana than you used. Cool adherence to lore, though.
Henlock - I like that the sacrifice is optional, I can't think of a card with an ability with that clause and it's very cool. Also, this is a very powerful but great-feeling card.
Subject16 - What a simple and flavorful uncommon! Since you have to sacrifice something big for it to get big, I kind of wish it also gained trample when you sacrifice, but it's still quite fun.
marioguy3 - As adorable as this is, I don't know if it's mythic! It's very cute, but ultimately just underwhelms me a bit, much as I like each component.
netn10 - A very interesting card as far as lore, and it does seem powerful. The idea of a saga creature is very cool but this doesn't feel like the creature IS a story. Cool effects, though!