So, to keep track of which creature is blocking, it's common for the defending player to place their blocking creatures in front of the attacking creatures to show which is blocking which
That first ability resembles the shenanigans you can get up to with Dargo, the Shipwrecker, so in the right deck, you can cast it for two mana, attack for seven (that can only be blocked by legendary creatures), and then sacrifice it to destroy an annoying artifact or creature
Casting Cost: Card Text: Red creatures you control get +1/+0
You can finally answer No to those blue players with birds, drakes, and spirits
or they even have something that should not be present on the card (see beta Volcanic Island's white dots)
Like, less than 1mm smaller