Cheapest priced copy (Masters 25): $0.35 at Card Kingdom, near mint, their price list as of .
Kavu Predator 
Creature — Kavu · 2/2 · Uncommon · Duel Decks: Heroes vs. Monsters · #46
Trample
Whenever an opponent gains life, put that many +1/+1 counters on this creature.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
4 printings · $0.35 to $1.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Masters 25 | 176 | Uncommon | $0.35 | $0.49 |
| Duel Decks: Heroes vs. Monsters | 46 | Uncommon | $0.35 | — |
| Planar Chaos | 132 | Uncommon | $0.49 | $1.99 |
| The List | PLC-132 | Uncommon | $0.35 | — |
3 rulings from Wizards of the Coast
- 16 March 2018Each creature with lifelink dealing combat damage is a single life-gaining event. For example, if two creatures an opponent controls with lifelink deal combat damage at the same time, Kavu Predator's ability will trigger twice. However, if a single creature an opponent controls with lifelink deals combat damage to multiple creatures, players, and/or planeswalkers at the same time (perhaps because it has trample or was blocked by more than one creature), the ability will trigger only once.
- 16 March 2018Kavu Predator's last ability triggers just once for each life-gaining event, whether it's 1 life from Kor Firewalker or 6 life from Renewed Faith.
- 16 March 2018If an opponent gains an amount of life "for each" of something (such as from Congregate), that life is gained as one event and Kavu Predator's ability triggers only once.