I'll admit I misinterpreted the first mention of Aurelia's Fury. However, Sliverguy420 you have just been correcting and fighting people in this thread. You called me out on my mistake, now let me return the favor:

"i never said magwaaf said anything."

"magwaaf wrong about what exactly? are you saying wotc deliberately did the opposite here, and that monocolored cards are more often stronger than their multicolored counterparts?"

Yes, you "technically" didn't say he said it, but you were asking. I answered you. Then:

"Thought Collapse and Psychic Strike do NOT in fact have the same effect. thats the "whole effing point". one mills 2, the other mills 3. not the same effect."

While the actual question was:

"What does everyone else say, about this? Why are some mono-colored cards more powerful than are multi-colored cards that are very similar?"

You suddenly denied the entire premise of the post just to spite me. That's not contributing, that's derailing. My argument about Aurelia's Fury was that they're not very similar. You start arguing that "very similar" is not exactly the same. That's not gathering or sharing any insight in the discussion at hand. You lose yourself in semantics to feel better about yourself correcting someone online on the Internet. And you dig your heels in the sand when someone else calls you out on it. I thought about making the point of your posts not contributing to the original question in my previous post, but someone beat me to it.

The exact same card with a different name you tried to pass on as the only true meaning of same, which only works for cards, not effects, has its own name. A functional reprint. That's the term to use when discussing cards that are the same, except for the name. They have no place in a discussion about similar cards with different measurements of power, because by definition they're the same in every way, and there is no difference in power.

Effects in Magic are things that happen as the result of a spell or ability. Countering a spell is an effect. Making a player mill cards is an effect. Dealing damage is an effect. Shock and Lightning Bolt both have the same effect, where one of the cards is more powerful than the other. Because they're both monocolored, I've not used the example in this topic. They make my powercreep argument a bit weaker as well. But the thing is: when somebody would claim they're the same card, they would obviously be wrong. But stating: these are not the same card, 2 damage is not 3 damage, you can't compare them, while no lies in the words, is also obviously wrong. Lightning Bolt is said to be "strictly better" than Shock. The same mana cost, card types, same effect, but one with higher numbers.

If Psychic Strike would also cost , we could just say Thought Collapse is strictly better. The discussion would end there, comparison easily handled. Because the mana cost is actually different, you could question if the mana cost causes the difference. That's what OP did, thinking that was the only difference between the cards. Limited environments, rarity and powercreep are all contributing to how strong a card could be, and could explain the mentioned deviation from the expected trend.

Saying similar cards are not exactly the same, does not explain anything about that. Asking if fellow forum user is saying [topic of discussion] is actually the case, does not explain. Denying to derail the discussion after not trying to contribute to the topic and being called out on it, does not help OP's insight to the case. Deflecting that the one you're fighting about it is now also derailing the topic, does not help.

That's what I think it's wrong about your presence in this topic, the ad hominem nature of every post you make, and whenever you're pointed to that, trying to cover it up with more of the same, unwilling to change your own perspective, but expecting us all to join yours. Seems I'm not the only one.

Or, hear me out, mill X is the effect I'm talking about, and mill 3 is stronger than mill 2, that way you can actually compare strength instead of just derail a discussion to have the last word.

It's the color that enables the type of effect, it's time of printing, rarity and amount of pips that could account for a scaling in power of specified effect. A more restrictive mana cost, making the spell harder to cast, allows for more powerful effects.

Colors have overlap in their effects, that's why mono- and multicolored cards can look similar.

But multicolor cards are usually a combination of effects from the different colors, that combination making the card usually more powerful in a vacuum. The card, not the effect. And when that's the case, there is no monocolored counterpart. Therefor there is no comparison.

"that monocolored cards are more often stronger than their multicolored counterparts?" - Sliverguy420

That's the topic of discussion yes, that's exactly the question that was asked in the original post, with given examples where exactly that is the case, and if there were any rule behind it. It was not magwaaf who said that, it was DemonDragonJ.

"you can't have a card that's weaker or stronger if the effects are the same."

Yes you can. Thought Collapse and Psychic Strike have the same effect, one is stronger. That's the whole effing point of discussion.

It's also mythic vs. uncommon, that alone would explain the increase in power. The added effects are very white, which is enough reason to explain why it's multicoloured. Aurelia's Fury as a mono red card would make no sense at all, bringing it up in a discussion about cards that, according to the title of the topic, are weaker in multicolored than in monocolored with the same effect for the same cost, is a) literally disproving the theory and b) not applicable because the effects are not the same in this case, and can only be explained by the mono-/multicoloured nature of the card.

That's why I didn't think it fits in the discussion, but it made a good point in my argument for powercreep as explanation of the suggested trend nonetheless.

The problem with printing cards that are rewards for monocolor decks, is that they're either just not good enough, like Slaying Fire or instant expensive staples, like Nykthos, Shrine to Nyx. Because if the effect is good enough, the two-color decks will consider playing it too, think Cabal Coffers+Urborg, Tomb of Yawgmoth. Monocolor decks make the sacrifice of devoting to that color, and accepting its weaknesses. The best way to combat those weaknesses, is to add a color. The payoff is the manabase consistency, and leveraging the strength of the color you picked. There's a few Caged Sun or Throne of Eldraine-type cards that possibly could slot in every monocolor deck. But the fun of building a monocolor deck (I'm talking commander here) is to deepen out your limited cardpool to get the job done in a way most multicolor decks won't expect because it uses cards you normally wouldn't see in multicolor decks.

To get back on topic, in the OPs examples, if the monocolored option for similar effect is actually better, it's probably printed more recently and therefor more powerful. That's the case with Psychic Strike vs Thought Collapse and for as similar as they are (differences were already pointed out) for Merciless Eviction and Farewell. Final Judgment in its turn is older than that, and therefor more limited in application than Merciless Eviction, which is the newer card out of the two.

Aurelia's Fury vs Rolling Thunder is a bad comparison. The silence- and tap effects make the card a lot more versatile. With Aurelia's Fury you could ping a player to stop them from comboing, tap down three blockers to swing in for lethal, where Rolling Thunder only offers straight up removal or burn to the face, which Fury can do as well. Still, Rolling Thunder was printed in 1997 where Aurelia's Fury was printed in 2015.

What OP's describing is powercreep, and it's not restricted by colors.

So you'd say that Phyrexian Vindicator is easier to cast than Omnath, Locus of Creation? is really restrictive as a cost.