Rem Karolus, Stalwart Slayer Boros players will be happy to play Rem Karolus in any of their aggro shells
For four mana, you get a 4/4 that lets you sacrifice a creature on attack to add Red mana equal to its power
The biggest takeaway from this graphic is where the gold line is respective to the top of each set's blue bar
For three mana, that's not the greatest rate in the world, but there are plenty of targets in multiple formats, and finding ways to get more interaction into your decks is always good
Ghost Quarter Rogue's Passage Reliquary Tower Waterfront District Various Blue/Black Lands Cycling Lands
Preventing blockers can enable significant damage to go through, deflecting a targeted spell can handle problematic permanents, and at worst, you can destroy an artifact