Here's some feedback: (it will be harsh, so be warned)
Maralen of the Evensong
{3}{w}{g}{b}
Legendary Creature - Elf Avatar
5/5
When you draw a card, you may discard it. If you do, you gain life equal to its converted mana cost.
When your opponent draws a card they may discard it. If they do not, they lose life equal to its converted mana cost.
First, the body: a 5/5 for 6cmc (3 generic + Abzan colors) is fine, though it feels unusual for an elf.
The first ability is honestly fine. It fuels graveyard strategies and gains life on the side. Nothing too harsh on a 6cmc creature. Also, please use "whenever", since the trigger usually doesn't occur only once.
The second ability needs a rewording, since it currently does not work. You'd want it to say: "Whenever an opponent draws a card, they may discard it. If they don't, they reveal that card and lose life equal to its converted mana cost." In your first iteration, the card isn't revealed, which causes all other players not to know its cmc. That's a problem.
Apart from that, the powerlevel shouldn't be too harsh, though if not met with removal, it will escalate quickly. That is fine for 6cmc.
Masukai, Lord of Spells
{4}{u}{u}{u}
Legendary Creature - Dragon Wizard
4/6
Flying
{u}{t} Counter target instant or sorcery spell.
{u}{u}{t} Return target instant or sorcery card from your graveyard to your hand.
{u}{u}{u}{t} You may play any number of spells returned by Masukai, Lord of Spells without paying their associated mana cost.
Again, first the body. 4/6 flying for 7cmc in mono blue is reasonable, especially given a suite of abilities.
Now for the first ability: it's a better
Dispel for the same mana cost once per round, more if you can untap. Definitely too strong. I'd consider it at 2U at least, otherwise I'd cut it. Even on a 7cmc creature, that ability is downright oppressive.
The second ability: hello, better
Snapcaster Mage! Same as with the first ability. Apart from the missing body of Snappy, this is far better, since it returns to your hand and doesn't
exile. All at instant speed, possibly repeatable. Maybe at 5cmc+.
The third ability: it just doesn't work. The game technically does not remember which cards you returned to your hand with the Commander's abilities. Also, what happens when those cards are in your graveyard or in
exile? Or worse, in your library? The condition could be applied to those cards. It's hard to track and frankly, a rules
nightmare. I don't know how to fix it.
Goorg the Furious
Planeswalker - Goblin Shaman
{2}{r}{r}
3
+1: Create a token 1/1 Goblin Warrior with haste.
-3: Destroy target creature, create a number of 1/1 Goblin Warrior tokens equal to destroyed creature's toughness.
-9: You get an emblem stating, "When a token creature you control dies, create two tokens that are a copy of that creature."
Oh, a planeswalker! Also, a blatant color pie break. But let's start slow:
2RR for a 3 loyalty planeswalker that can +1 is fine. Nothing to worry there. But now for the first thing I have my worries with:
The creature(!) types!. A planeswalker usually has its name as a (sub)type. In this case, the type would be "Legendary Planeswalker - Goorg". Planeswalkers with creature types don't sound impossible, but would be a very wild thing to do and probably invoke a rules
nightmare. Also, it lacks the "This planeswalker can be your commander." line, but let's ignore that.
Now, for the +1 ability: creating a single 1/1 Goblin (Warrior) token is perfectly fine and probably a very red thing to do. I'd cut the Warrior type and just do Goblins, for the sake of simplicity.
The -3 ability: absolute color pie break. A mono red card does never state "destroy target creature" in a singular sentence, especially not with an upside. As for destruction, let me help rephrasing it in a more Goblin tribal-esque and proper red way: "-3: You may sacrifice a Goblin. If you do, ~ deals
X damage to any target, where
X is the amount of Goblins you control."
The -9: Essentially a token doubling effect, which has, apart from Goblins and
Krenko, Mob Boss, no precedence in red, but in white and green. I think it would be fine if worded like this: "You get an emblem with: Whenever a Goblin token you control dies, create two tokens that are copies of it." This, while still game-ending strong, is hard to achieve, since you start with essentially four loyalty and need six further turns without
shenanigans like proliferate. It's fine that way.
Mishraele, General of Justice
Legendary Creature - Angel
{x}{w}{u}{r}
4/4
Flying, Hexproof
Enchanted creatures you control gain Hexproof.
Sacrifice Mishraele, General of Justice, you may search your library for any number of enchantment cards and put them in your hand.
Mishraele is definitely the worst offender of the four, because it's just that imbalanced.
But let's sort that out:
Body: 4/4 flying hexproof for 3cmc, Jeskai colors. The
X doesn't even do anything except existing. That's an insanely good body, especially in those colors.
Abilities: hexproof for enchanted creatures you control is fine, even at 3cmc. But: consider rewording it as "Other enchanted creatures you control have hexproof.", because Mishraele already has it. I'd even cut her own hexproof, because hexproofing your threats is pretty damn strong; compare to
Shalai, Voice of Plenty. It's most certainly a white and blue ability, red doesn't contribute here.
And now for the holy grail of imbalance: "Sacrifice Mishraele, General of
Justice, you may search your library for any number of enchantment cards and put them in your hand." This is broken on so many levels. Any number? It's strong at one or two enchantments, especially since you can instantly activate the sac ability on
entering the battlefield. Also, just sacrificing a 3cmc creature for that effect is insanity. It would be insanity on a 7cmc creature.
There are ways to fix it, though. Let's severely weaken it: "6, Sacrifice ~: Search your library for up to two enchantment cards, reveal them, and put them into your hand, then shuffle your library." This way, there is a decent cost to the ability, while still holding an insanely strong effect, since it can fetch two card combos.
Another gripe I have with this creature is the fact that there really isn't anything red to its abilities. White and blue, yes, compare to
Bruna, Light of Alabaster and, as above, Shalai. But nothing red at all. Red also doesn't deal with enchantments or hexproof. Even auras aren't exactly the red thing to have. You might consider just using WU.