The Boros defeat you not because any one piece is big and scary, but because the combination of all its little things is big and scary
If, for one of the targets, the player can't choose a new legal target, then it remains unchanged (even if the current target is illegal)
This is standard pracitce, but if you want to see the details of this, see the Jupyter notebook here
Cards to consider cutting: Highland Lake Swiftwater Cliffs Submerged Boneyard Dismal Backwater Crypt of the Eternals 1x Swamp Clone Confiscate Gyruda, Doom of Depths Nemesis Mask Beguiler of Wills Dire Fleet Neckbreaker Dire Fleet Ravager Tomb Robber Clone, Confiscate, Gyruda, Wills are four subpar cards here compared to the others to copy or gain control of something an opponent has
We have very similar tastes, this is also my childhood era