When Valki enters, each opponent reveals their hand. For each opponent, exile a creature card they revealed this way until Valki leaves the battlefield. {X}: Choose a creature card exiled with Valki with mana value X. Valki becomes a copy of that card.
Rulebreaker — If Valko Indorian, Researcher is your Commander, you may include all artifacts and enchantments in your deck regardless of color identity. Artifacts and enchantments you own everywhere become both types. (This applies to your library, hand, battlefield, and so on.) Whenever you cast an artifact or enchantment spell, put a +1/+1 counter on Valko Indorian.
Flying, lifelink At the beginning of each end step, if you gained 4 or more life this turn, create a 4/4 white Angel creature token with flying and vigilance.
Whenever a nontoken, non-Angel creature you control dies, return that card to the battlefield under its owner's control with a +1/+1 counter on it. It has flying and is an Angel in addition to its other types.
When Valkyrie's Sword enters, you may pay {4}{W}. If you do, create a 4/4 white Angel Warrior creature token with flying and vigilance, then attach Valkyrie's Sword to it. Equipped creature gets +2/+1. Equip {3}
Flash You may cast noncreature spells as though they had flash. Whenever you cast a noncreature spell, Birds, Frogs, Otters, and Rats you control get +1/+1 until end of turn. Untap them.
Gift a Food Creatures you control get +2/+0 until end of turn. If the gift was promised, target creature you control gains first strike until end of turn.
Menace Whenever Valley Rotcaller attacks, each opponent loses X life and you gain X life, where X is the number of other Squirrels, Bats, Lizards, and Rats you control.
We all share one life and one death. —Rotcaller saying
Whenever your team attacks with exactly two creatures, those creatures gain double strike until end of turn. Whenever chaos ensues, untap up to two target creatures your team controls. If it's a main phase, there is an additional combat phase after this phase, followed by an additional main phase.