You can take down a lot of dorks as well as transferring player damage to a Planeswalker, giving Arlinn a wide range of removal options
If Grim Flayer deals damage to your opponent one time, usually with the help of removal spells and Liliana, the Last Hope, then the game snowballs in your favor rapidly
Its not likely to make it into your zombie typal decks, which arent red that often anyway, but this card puts in exceptional work in a Feather, the Redeemed deck, for example
By combining two separate cards together, Meld creates one larger-than-life Creature or Planeswalker with true game-warping capabilities
At this point, however, thats looking unlikely
If Connive provides an elegant solution for flavor, why not use it