That might be card advantage from cards like Underworld Breach, Muldrotha, the Gravetide, and Osteomancer Adept, or it could be creature-based rewards from the likes of Sidisi, Brood Tyrant
The rest of em might as well not have power and toughness, because youre casting them only to blink them off your Soulherder
Fairly niche card, even when you play with it you usually don't want to have to find it and play it, but as it is the best at doing what it does it has retained its main cube slot
Run Patriarchs Bidding or Bontu-style recursion so one wrath doesnt end the game
Its also fast enough that it can often win before you get your walls up properly
In those cases, the effect of rolling a 6 applies only to his normal ability