Not only can it kill creatures on the spot heedless of most any restrictions, but, in failing that, it can also weaken an opposing creature
There are many abilities is Magic, which triggers to dealing combat damage
Some Art Series: Final Fantasy cards are actually worth a few bucks, with some of the more desirable ones reaching around $10-20
Flamekin Harbinger, of course, is also 1 mana and can tutor Rift...okay, are there more Elementals that synergize with exactly a hyperspecific Cascade line and are 2 mana or higher
Refunding one Red mana when casting instants or sorceries works well alongside Birgi, God of Storytelling, Veyran, Voice of Duality, and Baral and Kari Zev
By using some of Magic's most interesting lands and supporting them with spells and creatures to find them, Tricky Terrain eventually amasses enough power that nobody will ever look at lands the same way again