Cheapest priced copy (The List): $0.49 at Card Kingdom, near mint, their price list as of .
Mizzium Tank 
Artifact — Vehicle · 3/2 · Rare · War of the Spark · #138
Trample
Whenever you cast a noncreature spell, this Vehicle becomes an artifact creature and gets +1/+1 until end of turn.
Crew 1 (Tap any number of creatures you control with total power 1 or more: This Vehicle becomes an artifact creature until end of turn.)
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.49 to $1.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| The List | WAR-138 | Rare | $0.49 | — |
| War of the Spark Promos | 138p | Rare | $0.49 | $1.99 |
| War of the Spark Promos | 138s | Rare | — | $0.79 |
| War of the Spark | 138 | Rare | $0.49 | $0.49 |
2 rulings from Wizards of the Coast
- 3 May 2019Mizzium Tank's triggered ability resolves before the spell that caused it to trigger. It resolves even if that spell is countered.
- 3 May 2019Mizzium Tank's triggered ability triggers even if it's already a creature. In this case, it gets an additional +1/+1 until end of turn.