The critical strikes cause the next Smite or Flash Heal you cast within 15 sec to be instant.
To acquire the Surge of Light Rune, you'll need to defeat the Echo of a Lost Soul and obtain the Lost Tribe Prophecy from it. Here's a step-by-step guide:
1. Time and Location: The Echo of a Lost Soul spawns only between 9 PM and 6 AM server time. You can find it at various locations:
- Tanaris: Gadgetzan graveyard, coordinates /way 54.0 28.6
- Swamp of Sorrows: Graveyard southeast of Stonard, coordinates /way 50.4, 61.1
- Stranglethorn Vale: Ruins of Aboraz, coordinates /way 30.0 73.0
- Hinterlands: Graveyard northwest of Revantusk Village, coordinates /way 72.6 68.0
2. Defeat the Echo of a Lost Soul: Once you've located the Echo of a Lost Soul, engage it in combat. Be aware that it has a buff called "Protected by Shadows," granting immunity to Fire, Frost, Holy, Nature, Physical, and Shadow damage.
3. Overcoming Immunity: While the Echo is immune to most types of damage, you can effectively damage it with Arcane damage (using Stellar Fragments if you're a Night Elf) or a wand with Arcane damage. Alternatively, you can use several casts of your strongest Holy spell. After a few casts, you'll receive a message indicating that your holy magic has rendered the spirit vulnerable. Keep casting Holy spells until the Echo is defeated.
4. Loot the Lost Tribe Prophecy: Once the Echo of a Lost Soul is defeated, loot it to obtain the Lost Tribe Prophecy to get your Rune.