Cheapest priced copy (Foundations): $0.35 at Card Kingdom, near mint, their price list as of .
Joraga Invocation 
Sorcery · Uncommon · Foundations · #555
Each creature you control gets +3/+3 until end of turn and must be blocked this turn if able.
Legal inCommanderBrawlStandardPioneerModernLegacyVintage
Not legal inPauper
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Foundations | 555 | Uncommon | $0.35 | — |
| Magic Origins | 183 | Uncommon | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 22 June 2015If multiple attacking creatures must be blocked if able, the defending player must assign at least one blocker to each of them if possible. For example, if two such creatures were attacking and there were two potential blockers, they couldn't both be assigned to block the same attacker.
- 22 June 2015Joraga Invocation doesn't force any specific creature to block any specific attacking creature. The defending player still chooses how creatures they control block.