Lurrus of the Dream-Den Lets take a moment and talk about the companion mechanic
Size Sleeves Settlers of Catan Sleeves Square Sleeves Tarot Size Sleeves Binders, Portfolios, etc
One thing to note about Volo, Itinerant Scholar (aside from all those creature types) is that it has an ability called "choose a Background." Choose a Background is a very specific version of the partner ability, which can allow a player to have more than one commander
And, of course, the Pokmon company made good use of this quirky little creature
Relentless makers: Legion Warboss, Goblin Rabblemaster, Battle Cry Goblin, Goblin Warchief, Beetleback Chief, and Siege-Gang Commander keep bodies flowing
There isn't any good direct comparison to Mangara's abilities, but the closest thing that popped into my head is Runic Armasaur, another creature whose card drawing ability is entirely dependent on your opponents' actions, making the card inconsistent where it sometimes draws you zero cards and sometimes floods you with card draw