I think these would be nicer as charms with Entwine.
Swim's islandwalk is particularly disappointing as a combat trick, since it's only useful against the color most likely to counter your combat tricks or do something like Hydrosurge your fatty. It'd be nice for it to offer a broader threat.
Thrust/Parry breaks the cycle by helping attackers and blockers instead of helping attackers and screwing with blockers like the others.
Also, movexig said a lot of stuff that I agree with.
Regenerate each blocking creature. Those creatures gain deathtouch until end of turn.
// VillainyB
Instant [U]
Target attacking creature gets +X/-X until end of turn, where X is its toughness minus 1.
Push // G
Instant [U]
Target creature gains trample until end of turn. Remove each creature blocking it from combat.
// Pull1GG
Instant [U]
Draw a card for each creature that's attacking you. Those creatures lose flying until end of turn.
I want to make these feel as organic and intuitive as possible. That's going to mean two things:
Each card's flavor needs to make sense with its effects and colors.
The combat specifiers ("attack" and "block") can't feel tacked on.
But, these are split cards. Pretty much every split card feels "hot-glue-gunny." (Are you going to say that Wax//Wane feels like a unified whole?) I'm going to go farther, and say that split cards SHOULD feel like two random things tacked onto one another. I want each side of the card to be usable in a very different situation.
That said, I have taken heed of some of the comments made, above, and I have some revisions prepped for the three cards in the OP. Here they are:
Thrust // 1WW
Instant [U]
Attacking creatures get +1/+0 and gain first strike until end of turn. Untap those creatures.
// ParryW
Instant [U]
Prevent all damage that would be dealt to target blocking creature this turn.
Sink // 1UU
Instant [U]
Put target blocking creature into its owner's library first, second, or third from the top.
// SwimU
Instant [U]
Attacking creatures get +0/+1 and gain islandwalk until end of turn.
Wear // R
Instant [U]
Attach target Equipment to target attacking creature. (Control of the Equipment doesn't change.)
// Tear1RR
Instant [U]
Tear deals 3 damage to target blocking creature and 3 damage to that creature's controller.
I'll probably still make some revision to these... they're not easy to design!
It's especially bad when the two sides are similar in both function and size.
I guess I was thinking that the CMC 1 / CMC 3 split that I had going for this cycle was enough of a mana cost difference. You seem to think that it isn't. That's a fair stance to take - what would be an acceptable difference, all other things being equal?
I'm not going to make these into multicolor splits because this isn't a multicolor set. But, I think that along with the mana cost difference (whatever it happens to be, in the end) the attacking / blocking split is enough of a thematic hinge upon which I can set this cycle.
I do find it curious that you're concerned about the effects of each half being too similar, but you're also promoting Boom//Bust as a good example of how to do monocolor splits correctly. I'm getting a little bit of a mixed message, here.
I'll be the first to admit that I want to extract a little bit more juice out of this cycle than I am currently extracting. Like I said, designing these is HARD... but I think that the journey is worthwhile. Here are a few ideas I'm thinking about to spruce this up:
One half CMC 1, one half costed XCC.
One half being uncastable, like Evermind, but generating some kind of effect.
The more expensive half sporting a triple-C requirement and generally being huge.
One half always generating a token of some sort that ETB's blocking an attacking creature.
Instant [U]
Attacking creatures get +1/+0 and gain first strike until end of turn. Untap those creatures.
Instant [U]
Target blocking creature gains protection from the color of your choice until end of turn.
Instant [U]
Put target blocking creature on top of its owner's library.
Instant [U]
Attacking creatures gain islandwalk until end of turn.
Instant [U]
Attach target Equipment to target attacking creature. (Control of the Equipment doesn't change.)
Instant [U]
Tear deals 2 damage to each blocking creature. Unattach all Equipment from those creatures.
Swim's islandwalk is particularly disappointing as a combat trick, since it's only useful against the color most likely to counter your combat tricks or do something like Hydrosurge your fatty. It'd be nice for it to offer a broader threat.
Thrust/Parry breaks the cycle by helping attackers and blockers instead of helping attackers and screwing with blockers like the others.
Also, movexig said a lot of stuff that I agree with.
Instant [U]
Regenerate each blocking creature. Those creatures gain deathtouch until end of turn.
Instant [U]
Target attacking creature gets +X/-X until end of turn, where X is its toughness minus 1.
Instant [U]
Target creature gains trample until end of turn. Remove each creature blocking it from combat.
Instant [U]
Draw a card for each creature that's attacking you. Those creatures lose flying until end of turn.
That said, I have taken heed of some of the comments made, above, and I have some revisions prepped for the three cards in the OP. Here they are:
Instant [U]
Attacking creatures get +1/+0 and gain first strike until end of turn. Untap those creatures.
Instant [U]
Prevent all damage that would be dealt to target blocking creature this turn.
Instant [U]
Put target blocking creature into its owner's library first, second, or third from the top.
Instant [U]
Attacking creatures get +0/+1 and gain islandwalk until end of turn.
Instant [U]
Attach target Equipment to target attacking creature. (Control of the Equipment doesn't change.)
Instant [U]
Tear deals 3 damage to target blocking creature and 3 damage to that creature's controller.
I guess I was thinking that the CMC 1 / CMC 3 split that I had going for this cycle was enough of a mana cost difference. You seem to think that it isn't. That's a fair stance to take - what would be an acceptable difference, all other things being equal?
I'm not going to make these into multicolor splits because this isn't a multicolor set. But, I think that along with the mana cost difference (whatever it happens to be, in the end) the attacking / blocking split is enough of a thematic hinge upon which I can set this cycle.
I do find it curious that you're concerned about the effects of each half being too similar, but you're also promoting Boom//Bust as a good example of how to do monocolor splits correctly. I'm getting a little bit of a mixed message, here.
I'll be the first to admit that I want to extract a little bit more juice out of this cycle than I am currently extracting. Like I said, designing these is HARD... but I think that the journey is worthwhile. Here are a few ideas I'm thinking about to spruce this up: