Cheapest priced copy (Ravnica Allegiance): $0.39 at Card Kingdom, near mint, their price list as of .
Galloping Lizrog 
Creature — Frog Lizard · 3/3 · Uncommon · Ravnica Allegiance · #175
Trample
When this creature enters, you may remove any number of +1/+1 counters from among creatures you control. If you do, put twice that many +1/+1 counters on this creature.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.39 to $2.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Ravnica Allegiance | 175 | Uncommon | $0.39 | $2.99 |
3 rulings from Wizards of the Coast
- 25 January 2019If Galloping Lizrog leaves the battlefield after its ability has triggered, you may remove any number of +1/+1 counters from among your creatures, even though you won’t put any on Galloping Lizrog.
- 25 January 2019If an effect causes Galloping Lizrog to enter the battlefield with +1/+1 counters on it, you may remove those counters with its triggered ability and put twice as many back on it.
- 25 January 2019You remove counters and put new ones on Galloping Lizrog all while its ability is resolving. Nothing can happen between the two, and no player may choose to take actions.