Obviously the ability to cast a card that costs three or less for free is a major plus, but if Yahennis Expertise ends up being an unreliable or too-slow sweeper, then it wont be played enough to warrant this slot
There have been plenty of discussions in the past about the dangers of a banned-as-companion list: it's one more list you have to track and adds complexity, among other reasons
Make sure you pack in some sacrifice outlets for quick access to your cached cards and to prevent your opponents from exiling Toluz, making the stored cards moot
Here are all three of those new cards: For me, the standout card here is easily Oscorp Industries, a Rare land with Mayhem, which means it can be played from your graveyard if you discarded it that turn
For example, if youre using a commander like Gishath that cares about a single creature type, include cards like Icon of Ancestry that let you choose a creature type to apply an effect to, as well as cards that care about your specific creature type (like Thunderherd Migration in the case of Gishath)
