As long as youve got information about your opponents cards, you can always turn off a huge portion of their deck
It's a blue MTG enchantment that costs one generic and one blue mana to cast
It reminds me a lot of Ragavan, Nimble Pilferer in that both cards seem to be the absolute peak of what you could expect for their respective mana costs
Every time your opponent casts a spell, you're able to draw a card unless they pay a tax of one additional generic mana
This made it a far more important card than its numbers would indicate because it made an entire deck exist for a long time, and in some cases Aluren was the only viable combo strategy available and taking it away would have radically altered the balance
Lightning Bolt, on the contrary, isnt legal in Standard or Pioneer, so its Thrum of the Vestige version from FCA is also unplayable in those formats