Its hard to think that a player wont win a game after having two additional combat steps
In most matchups, you will bring in some combination of cards to prepare against their hate cards unless they have nothing, and against fair decks youll usually sideboard in Show and Tell as an alternate game plan
Having access to both of Belunas potential effects in the command zone grants a huge amount of flexibility to your plays, and her color identity gives you access to a wide variety of adventures to stack your deck with
For many, this is an incentive to select a commander that is of several colors, as it opens up access to a larger card pool
The new legend Ratadrabik of Urborg is also a good thought, giving you vigilant zombies whenever one of your legends die, plus draw from Calgar himself
The extra part of generating mana of any color gets better if you have changelings, aliens, or doctors