Cheapest priced copy (Commander Masters): $12.99 at Card Kingdom, near mint, their price list as of .
Savage Beating 
Instant · Rare · Darksteel · #67
Cast this spell only during combat on your turn.
Choose one —
• Creatures you control gain double strike until end of turn.
• Untap all creatures you control. After this phase, there is an additional combat phase.
Entwine {1}{R} (Choose both if you pay the entwine cost.)
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
4 printings · $12.99 to $24.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Masters | 252 | Mythic | $12.99 | $13.99 |
| Commander Masters | 548 | Mythic | — | — |
| Darksteel | 67 | Rare | $13.99 | $19.99 |
| Marvel Universe | 26 | Mythic | $14.99 | $24.99 |
One ruling from Wizards of the Coast
- 1 December 2004The additional combat phase is directly after the combat phase in which Savage Beating is cast. There isn't a main phase between the two combat phases.