Reunion of the House can return any combination of creature cards whose powers total 10 or less. For example, it could target ten 1/1 creature cards, two 5/5 creature cards, and so on. Regardless of what other creature cards you choose as targets, you can also choose any number of creature cards with power 0 as targets.

If the power of the target creature cards changes while in your graveyard, most likely because one has a characteristic-defining ability that defines a * in its power, the total power of the creature cards may become greater than 10. If this happens, the entire selection of targets is illegal. In this case, Reunion of the House won’t resolve and none of its effects will happen. Nothing will be returned to the battlefield, and Reunion of the House will be put into its owner’s graveyard.

Use the power of the creature cards as they exist in your graveyard to determine whether they can be the targets of Reunion of the House. For example, a 0/0 creature card that will enter the battlefield as a copy of a 15/15 creature can be returned, as can five 0/0 creature cards that will each enter the battlefield with three +1/+1 counters on them.