Felwar Stone isnt bad but if you don't play 2 mana rocks I prob wouldn't play stone. Those tend to all generically play the same i.e. providing ramp to non-green decks and minimizing green's impact in that regard. A few don't break the bank, but they exponentially get more noticeable.
Maze of Ith is very much an unfun card. Some people also think it sucks, I don't personally but against some strategies it does. It's a card that either shuts down your opponent or feels like a wasted card, tends to be closer to the former than the latter.
Magus of the Moon is probably better in limited/cube than Blood Moon, as Blood Moon is mostly famine until you feast hard. I've definitely seen decks that would fold to Blood Moon, but most other decks are running 5-10 basics. At least Magus can attack, which is better even if its more fragile since Blood Moon effects are feast or famine.
Ashes to Ashes was great in Pauper, but Pauper is grindy. If your format is grindy enough and slow enough to want that AND not get punished by the 5 life it's good, but there's probably plenty of better black removal that won't dome you for a quarter of your life.
Elves tend to always be good. Deep Shadow proves the life barely matters, and even Boreal Druid proves the color doesn't matter. It's probably the safest to add unless you don't run elves.
Ball Lightning is OK, but I'd rather run something like the 3/3 wither haste that's gruul hybrid and just make that work instead. It's fine if you need a curve topper and plays better than Im giving it credit for, but it really only fits in one deck and is useless outside of it.
Maze of Ith is very much an unfun card. Some people also think it sucks, I don't personally but against some strategies it does. It's a card that either shuts down your opponent or feels like a wasted card, tends to be closer to the former than the latter.
Magus of the Moon is probably better in limited/cube than Blood Moon, as Blood Moon is mostly famine until you feast hard. I've definitely seen decks that would fold to Blood Moon, but most other decks are running 5-10 basics. At least Magus can attack, which is better even if its more fragile since Blood Moon effects are feast or famine.
Ashes to Ashes was great in Pauper, but Pauper is grindy. If your format is grindy enough and slow enough to want that AND not get punished by the 5 life it's good, but there's probably plenty of better black removal that won't dome you for a quarter of your life.
Elves tend to always be good. Deep Shadow proves the life barely matters, and even Boreal Druid proves the color doesn't matter. It's probably the safest to add unless you don't run elves.
Ball Lightning is OK, but I'd rather run something like the 3/3 wither haste that's gruul hybrid and just make that work instead. It's fine if you need a curve topper and plays better than Im giving it credit for, but it really only fits in one deck and is useless outside of it.