If one of Dragon's Rage's targets dies from a card effect (like Hidden Blade) before Dragon's Rage resolves, does the other target still take damage?

Ruling: No, the surviving unit takes no damage. When a unit dies before Dragon's Rage resolves, it has 0 might (or null), so there is no damage to deal.

Nuances:

• The rule allowing effects to "look back" at a unit's last known information only applies to the spell/effect that caused the zone change, not to other effects resolving afterward
• Hidden Blade can look back to find the unit's controller because it caused the death, but Dragon's Rage cannot look back to find the unit's might because it didn't cause the death