Some common blue 4 drops:

Torpor Drake
Creature - Drake
Flying
Whenever ~ attacks, target creature an opponent controls doesn't untap during its controller's next untap step.
2/2

Skulking Ox
Creature - Ox
Skulk
2/4

Enrage
Also, Culling Blade should cost more IMO because of the split second.

I think it's fair. It's multicolored, and it's gonna be really frustrating to draw in multiples when you need to burn them out or kill a fatty.

Pessimistic Haruspex
Creature - Human Wizard
Sacrifice a creature: counter target spell unless its controller pays x, where x is that creature's power.
3/6
"According to my consultation with the unspeakable powers of the underworld, nope."

Clement, Captain of Secrets
Legendary Creature - Hound Advisor
When ~ enters the battlefield, target opponent names 2 cards. Search your library for a creature card with neither of those names, reveal it, put it into your hand, then shuffle your library.
3/3

Henrik, the Admiral
Legendary Creature - Hound Warrior
Whenever ~ attacks or blocks, you may remove it from combat. If you do, it deals damage equal to its power to target opponent.
3/3

Daryl, the Frigid
Legendary Creature - Elemental Wizard
Sacrifice a permanent: creatures your opponents control attack or block this turn if able.
3/3

Xu, the Harvester
Legendary Creature - Human Druid
: ~ fights target creature. When that creature dies this turn, put an artifact token named "gold" onto the battlefield. It has "sacrifice gold: add one mana of any color to your mana pool."
3/3

Alexander the Fourth
Legendary Creature - Human Cleric
Whenever a creature you control blocks or becomes blocked, destroy that creature and each creature blocked by or blocking it.
3/3

Some multicolored versions of the legends I made for Catarinia. These aren't part of the set, but I felt like making them.

Vogol, the Twisted Cycle
Legendary Creature - Demon Druid
Flying
At the beginning of your upkeep, choose one:
-Put a 1/1 green saproling creature token onto the battlefield
-Each player sacrifices a creature.
3/3
"The continuous extinguishing of life requires its continuous creation."

Yris, Citadel Tactician
Legendary Creature - Human Soldier
Whenever ~ or another creature you control attacks or blocks, target creature gets -1/-1 until end of turn.
2/2
"I'm grateful to Eriel for his sanctimonious moralizing. It helped me realize that I'm not a good person."

Oszar, the Machinator
Legendary Creature - Human Advisor
Whenever a creature an opponent controls dies, you may sacrifice a creature. If you do, put that creature onto the battlefield under your control.
2/2
"I've always been ruthless, but only now am I becoming clever enough to see the possibilities opened up by my ruthlessness."

Darthos, Protector of Life
Legendary Creature - Human Druid
Other creatures you control get +1/+1.
When ~ dies, put a +1/+1 counter on each creature you control.
2/2
"Nature is amoral and selfish, and I love it. But to preserve it, I must be moral and selfless."

Eriel, the Righteous
Legendary Creature - Angel
Flying
Creatures you control have battle cry and attack and block each combat if able.
3/4
"It makes no difference that Yris has joined Oszar's host. She was always a sinner, and so always an enemy."

Joshua
Legendary Creature - Turtle
: Draw a card.
1/4

Pellium, the Humanist
Legendary Creature - Human Wizard
Whenever you cast a noncreature spell, creatures you control gain protection from the color of your choice until end of turn.
2/2
"All the universe would ring hollow were it not of the people who inhabit it."

Brulgar, the Untamed
Legendary Creature - Beast
Whenever a creature you control becomes blocked, that creature deals damage equal to its power to target opponent.
4/4
"She considers me 'domesticated' since I allied myself with the garrison, and is determined that the same fate should not befall her."
-Darthos, Darkwood Druid

Naro, the Reaver
Legendary Creature - Elemental
Haste
: ~ deals 1 damage to target creature or player.
Sacrifice a creature: ~ gains deathtouch until end of turn.
"Where there was once only playful destructiveness, there is now a definite malice, a certain cruelty to him."
-Tritia, Caller of Storms
3/3

Tritia, Archmage
Legendary Creature - Human Wizard
: Each player draws a card, then ~ deals damage to each player equal to the number of cards in their hand.
2/2
"I never wanted to become a wizard, but I want a lot of things that are easier to get if you're a wizard."

Yris feels like Umezawa's Jitte

Bound by Contract
Enchantment - Aura
Enchant creature
Enchanted creature can't attack
Extort

A new mechanic, charging:

Charging (Whenever this creature attacks or blocks, put a charge counter on it.)

Dwarven Sniper
Creature - Dwarf Soldier
First strike, Charging
Remove 3 charge counters from ~: ~ deals 1 damage to target creature or player.
1/1

Charging Bear
Creature - Bear
Charging
Remove 3 charge counters from ~: ~ gets +3/+3 and gains trample until end of turn.
2/2

Dazzling Priest
Creature - Human Cleric
Charging
Remove 3 charge counters ~: target creature gains indestructible until end of turn.
2/3

Merfolk Siren
Creature - Merfolk Wizard
Charging
Remove 3 charge counters from ~: tap up to two target creatures. They don't untap during their controller's next untap step.
2/4

Wraith Knight
Creature - Wraith Knight
Charging
Remove 3 charge counters from ~: return target creature card from your graveyard to your hand.
4/4

Snowball Fight
Enchantment
Creatures have ": Tap target creature."

Shadow Elemental
Creature - Elemental
Skulk
When ~ attacks, you may have target creature get -2/-0 until end of turn.
4/4

Light Elemental
Creature - Elemental
Vigilance
: Tap target creature.
4/4

Battle Elemental
Creature - Elemental
Menace
When ~ attacks, you may have each creature get +2/+0 until end of turn.
4/4

Culling Blade is totally Mardu not Rakdos

How is it white? The only precedents I can find for destroying low toughness creatures are Fleshpulper Giant and Strangling Soot, and making your opponent lose the game is a black effect (Phage, Triskaidekaphobia, Vraska).

Grum, the Hunter
Legendary Creature - Goblin Warrior
When ~ enters the battlefield, put 2 1/1 red hound creature tokens onto the battlefield.
If a source would deal damage to ~, you may have that source deal damage to a hound creature you control instead.
3/1

Maurice, the Thief
Legendary Creature - Human Rogue
When ~ deals combat damage to a player, that player reveals their hand, and you may exile a nonland card from it until ~ leaves the battlefield.
You may play cards exiled with ~.
3/3

Should be RW imo

You're right.

I guess it feels white cuz exile. Also split second makes it feel kinda… idk heavensent. Also it totally seems like a spell Razia would use

More dota cards:

Blame Allocator
Creature - Troll Shaman
When ~ dies, sacrifice another creature.
4/4

Caustic Shrike
Creature - Bird Horror
Flying
Whenever Caustic Shrike deals combat damage to a player, creatures that player controls get -1/-0 until the beginning of your next upkeep.
2/2

Stab in the Back
Instant
Target creature gets -2/-2 until end of turn. If that creature is tapped, it gets -4/-4 until end of turn instead.
If you aren't paying attention in Duskmantle, you'll end up with a dagger in your back. If you're paying attention, you'll get one in the gut instead.

Gloorx Vloq, Lord of Shadows
Legendary Creature - Demon
Haste
Whenever ~ attacks, creatures you control gain lifelink and "whenever this creature deals combat damage to a player, that player sacrifices a permanent" until end of turn.
5/5

Lom Lobon, Lord of Magic
Legendary Creature - Demon
Prowess
At the beginning of your upkeep, shuffle your library, then exile cards from the top of your library until you reveal an instant or sorcery card. You may cast that card without paying its mana cost. If there is an X in that card's converted mana cost, x=5.
5/5

Mnoleg, Lord of Radiation
Legendary Creature - Demon
Infect
Spells your opponents control cost more to cast for each poison counter they have.
5/5

Cerebov, Lord of Fire
Legendary Creature - Demon
Double Strike
: ~ deals 5 damage to target creature or player. This damage can't be prevented.
5/5

The Seraph
Creature - Angel
Flying, Absorb 2
If a source would deal damage to you or a permanent you control, that source deals damage to ~ instead.
5/5

Mennas, the Silent
Legendary Creature - Angel
Flying
When ~ enters the battlefield, target player can't cast spells until the beginning of your next upkeep.
4/4

Tukima, Ballroom Mage
Creature - Human Wizard
Equipment you control have living weapon.
Germ creatures you control have haste.
When ~ enters the battlefield, exile each equipment you control, then return it to the battlefield under your control.
2/3

Pikel, the Slaver
legendary Creature - Kobold
When ~ enters the battlefield, put 3 1/1 white slave creature tokens onto the battlefield.
When ~ dies, target opponent gains control of each slave you control.
3/3

Divine Rapier
Artifact - Equipment
Equipped creature gets +4/+0 and has first strike.
When ~ enters the battlefield, attach it to target creature you control.
Whenever equipped creature dies, attach it to target creature an opponent controls. If you do, that creature's controller gains control of ~.
Equip