From WoWWiki
| Surge of Light |
|---|
| Your spell criticals have a X% chance to cause your next Smite or Flash Heal spell to be instant cast, cost no mana but be incapable of a critical hit. This effect lasts 10 sec. |
| Usable by |
|---|
| Class | Priest |
| Properties |
|---|
| Location | Holy, Tier 6 |
| Affects | Smite, Flash Heal |
| Ranks | 2 |
| Requirements |
|---|
| Points required | 25 |
| Related buff |
|---|
|
Surge of Light is a Priest Talent giving critical strikes a chance to remove the mana cost and cast time of the next Smite or Flash Heal.
Rank table
| Rank | Chance to Proc
|
| 1 | 25%
|
| 2 | 50%
|
Notes
Using with Smite
In this case you should note that besides increasing efficiency, Surge of Light also slightly affects effectiveness of Smite by taking 1 Global cooldown to cast Smite with zero crit chance. The highest DPS gain from this talent is achieved with a critical strike chance of 29%. After this point, the effectiveness bonus slowly decreases with each additional percent crit chance. At 67% crit chance, Surge of Light actually decreases Smite DPS, although this is more of a theoretical value.
Using with Flash Heal
While note above still actual for "Surge healing", there is at least one more thing to take into consideration. You may wish to increase your mana efficiency with these mana-free casts, but doing that requires you to make additional instant cast and thus, use extra Global cooldown. As Flash Heal is minor (that is the main difference from "Surge Smiting", where you will cast the same Smite spell, not some minor variation) healing spell and provides relatively little heal, "Surge healing" may sometimes reduce your HpS. On other hand, you will often have some kind of instant-cast "emergency spell", if you get enough critical heals to keep Surge of Light buff up for most of the time. This instant-cast heal may be used when your common Power Word: Shield is unavailable, for example, due to Weakened Soul debuff. Consider these notes before deciding, if you want to spend your talent points in this way or not. This talent is very useful in pvp cause its instant cast ability could make the difference between life or death.
