Divination reads that During your turn, whenever you draw a card, you may move 1 damage counter from chosen character to chosen opposing character, which in itself is a powerful opportunity to decrease damage, and either on the card itself or on others, and equally place this on other characters, rather than having to use up your opportunity to quest to do so, is powerful
2 Herald of Slaanesh While Heartless Summoning is a card comparable to Urza's Incubator that's right at home in a Demon-tribal deck, Heral of Slaanesh is a creature that was specifically created to be Demon-tribal's own highly offensive cost reducer
It does also make it more valuable to remove for those players and with not assuring a card unless you have two mana spare when it is removed it seems a little risky
However, there are a few important rules to keep in mind when trying to make good use of commander damage
Every player in the group (ideally four), will pick up a different Commander precon - the ready-to-play decks released by Wizards for the format