There are some clear, high-value cards you might have heard of Mana Reflection, Dryad of the Ilysian Grove, and Dark Depths
One of the reasons it became such a staple is that it let you deal with a card type you otherwise couldn't in red, and it always offers the possibility they can whiff into an instant or sorcery or land
This can help you accumulate the cost needed for Hyper Beam, which does 50 damage and lets you flip a coin to see if you can discard one of your opponents Energy cards.
This creature has trample as long as it has ten or more +1/+1 counters on it
That said, some crossovers feel like they come right out of left field
If youre playing a deck that relies on +1/+1 counter synergies, Inspiring Call is a great way to restock and avoid being punished by a board wipe after emptying your hand