During your opponent's turn (Quick Effect): You can target 1 "Ritual Beast" card you control and 1 card your opponent controls
IMPORTANT Kindly notice that because this item is already past the cut-off date, it can no longer be cancelled once an order has been placed for it
So this gets over almost every single monster in the game that cant be targeted
Another way to look at this exchange is to look at what Siege Rhino would look like if we made the trade in the other direction: Alt Universe Siege Rhino WBG Trample 5/6 That would be a pretty incredible card, clearly better than anything theyve done in that vein, but that is basically the rate Siege Rhino is at
The Sideboard The cards in our sideboard are designed to do three things: help improve our matchup against aggressive creature decks (by far our worst matchup), fight three-mana planeswalkers (especially Teferi, Time Raveler but also Narset, Parter of Veils and Oko, Thief of Crowns), and answer graveyard-based decks (which we actually help by filling their graveyard with our mill spells)