Cheapest priced copy (Commander 2021): $0.49 at Card Kingdom, near mint, their price list as of .
Pia Nalaar 
Legendary Creature — Human Artificer · 2/2 · Rare · Kaladesh · #124
When Pia Nalaar enters, create a 1/1 colorless Thopter artifact creature token with flying.
{1}{R}: Target artifact creature gets +1/+0 until end of turn.
{1}, Sacrifice an artifact: Target creature can't block this turn.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
3 printings · $0.49 to $0.59 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2021 | 177 | Rare | $0.49 | — |
| Kaladesh | 124 | Rare | $0.49 | $0.49 |
| Kaladesh Promos | 124s | Rare | — | $0.59 |
2 rulings from Wizards of the Coast
- 20 September 2016Once a creature has blocked an attacking creature, activating Pia Nalaar's last ability won't cause the attacking creature to become unblocked.
- 20 September 2016The “legend rule” cares about legendary permanents with the exact same English name. The Kaladesh™ card Pia Nalaar and the Magic Origins™ card Pia and Kiran Nalaar have different names, so you can control both at the same time.