A creature attacks alone if it's the only creature declared as an attacker during the declare attackers step (including creatures controlled by your teammates, if applicable)
Ive been enjoying it so much that I havent dismantled it in the pursuit of another deck (the fate of the vast majority of my EDH decks)
To tie all three abilities together, each requires a specific card type be exiled from a graveyard (note it doesn't have to be yours)
They dont have a coherent set of mechanics or abilities associated with them, but they do tend to be either hard to remove in some way or somehow disruptive or both
While this effect was designed at a time in which mana burn was still a rule of Magic, causing unspent mana to deal damage to its owner, but now it's quite helpful for those looking to access political bargaining chips in the midst of Commander games
Thank you for reading, and have an [card]Enchanted Evening