Cheapest priced copy (Ixalan Promos): $0.49 at Card Kingdom, foil, near mint, their price list as of .
Tilonalli's Skinshifter 
Creature — Human Shaman · 0/1 · Rare · Ixalan · #170
Haste
Whenever this creature attacks, it becomes a copy of another target nonlegendary attacking creature until end of turn.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
2 printings · $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Ixalan Promos | 170s | Rare | — | $0.49 |
| Ixalan | 170 | Rare | $0.49 | $0.49 |
8 rulings from Wizards of the Coast
- 29 September 2017If an effect from a resolving spell or ability, such as that of Rallying Roar, begins to apply to Tilonalli’s Skinshifter before it becomes a copy of another creature, that effect will continue to apply.
- 29 September 2017If Tilonalli’s Skinshifter copies a creature that’s copying something else, it will become whatever the target is copying.
- 29 September 2017If the target of the ability of Tilonalli’s Skinshifter becomes an illegal target, Tilonalli’s Skinshifter won’t become a copy of anything. It will remain a 0/1 attacking creature.
- 29 September 2017Tilonalli’s Skinshifter copies the printed values of the target creature, plus any copy effects that have been applied to it. It won’t copy counters on that creature or effects that have changed its power, toughness, types, color, or so on.
- 29 September 2017Once the ability of Tilonalli’s Skinshifter resolves, its new characteristics don’t change if the characteristics of the copied creature change or if the copied creature leaves the battlefield.
- 29 September 2017Tilonalli’s Skinshifter remains a copy of the creature through the end step. Damage is removed from it at the same time that it stops being a copy.
- 29 September 2017Because attackers have already been declared, any abilities Tilonalli’s Skinshifter copies that trigger when it or other creatures attack won’t trigger.
- 29 September 2017Notably, Tilonalli’s Skinshifter won’t copy effects that make a noncreature permanent become a creature. If this causes Tilonalli’s Skinshifter to stop being a creature, it’s removed from combat.