Most useful with "Number 39: Utopia", since if you Special Summon it from the Graveyard by other means, it'll destroy itself when selected as an attack target. So, when the replay occurs, activate this card to defend yourself.
"Neo Galaxy-Eyes Photon Dragon", is the second strongest monster that can be revived with this card immense 4500 ATK and the ability to gain more ATK and able to attack more than once, at the cost of only 1 Xyz Material, which this card will provide.
Activate this card in response to a Special Summon effect for a Level 5 or higher monster. Your opponent will waste that Special Summon card or effect if you use "Xyz Reborn" on "Evilswarm Ophion".
"Paleozoic Anomalocaris" and "Paleozoic Opabinia" are dependent on having Trap Cards attached to them as Xyz Material in order to use their third effects, thus Special Summoning them from the Graveyard with this card's effect is especially beneficial to them.