Cheapest priced copy (Commander Legends: Battle for Baldur's Gate): $0.35 at Card Kingdom, near mint, their price list as of .
Slaughter the Strong 
Sorcery · Uncommon · The List · #CMR-48
Each player chooses any number of creatures they control with total power 4 or less, then sacrifices all other creatures they control.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
7 printings · $0.35 to $7.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Legends: Battle for Baldur's Gate | 43 | Uncommon | $0.35 | $0.49 |
| Commander Legends | 48 | Uncommon | $0.35 | $0.49 |
| The List | CMR-48 | Uncommon | $0.35 | — |
| Rivals of Ixalan Promos | 22p | Rare | $1.29 | $7.99 |
| Rivals of Ixalan Promos | 22s | Rare | — | $3.49Out of stock |
| Rivals of Ixalan | 22 | Rare | $0.49 | $1.99 |
| Tarkir: Dragonstorm Commander | 131 | Uncommon | $0.35 | — |
3 rulings from Wizards of the Coast
- 10 November 2020If a creature's power is somehow less than 0, it subtracts from the total power of the other creatures its controller chooses. This can cause creatures with power 5 or greater to survive.
- 10 November 2020As Slaughter the Strong resolves, first the player whose turn it is chooses which creatures will be spared, then each other player in turn order does the same knowing the choices made before them. Then all the creatures not chosen are sacrificed simultaneously.
- 10 November 2020Slaughter the Strong has each player choose any number of creatures and then checks that the total power of creatures each player chose this way is 4 or less. For example, you could save two 2/2 creatures, or a 1/1 and a 3/3 creature, but not all four of those creatures.