The Sky Temple is one of the trickiest maps Heroes of the Storm has to offer, mainly because it relies on an indirect means of breaking through the enemy's defenses.
Capturing Sky Temples
This three-lane battleground features special temples of power at the north, center, and south. One of these temples will activate at random, giving teams a chance to take them over and harness their power. They're guarded by powerful and hostile creatures, and Heroes will have to fight them while staying in the circle in order to win the temple. You don't have to defeat all of them - just enough to gain you control. But you need to have at least one Hero sitting in the circle, so it might be a good idea to take them all out. Once a team has control of a temple, energy will erupt from its tower, aimed squarely at the opposing team's defensive structures. It's just a matter of time before the temple completely wrecks the defensive structures.
The opposing team must minimize the damage by fighting to control the temple for themselves. That could mean that temples spend a lot of time trading hands. At least one member of the controlling team needs to stay on the circle, even as the guardians resurrect themselves and attack anew.
Divide and conquer: There is some down time before the first temple activates at the start of the match. That gives your team an opportunity to spread out across the three lanes (preferably in a 3, 1, 1 style, but 2,2,1 across the lanes works too) in order to gain as much experience as possible.
Memorize the patterns: Although the temple activations become random, they are predictable within in the first few phases. The first temples to activate will always be the top and middle ones. Then the next phase activates the bottom one. Phase three will always include the bottom temple, while the second one is random. Every phase after that is unpredictable, but knowing the starting patterns gives you a significant advantage early on.
Grow in Power: Heroes will skirmish while contesting over temples. However, you might use the fights as a distraction to send or two teammates to gain experience through the lanes. The faster your team grows in power, the easier it'll be to take the temples or take the various mercenaries and bosses located throughout the map.
Become an Opportunist: Mercenaries are of especially high use on the Sky Temple map. Pick up a mercenary a few seconds before the temples are ready to activate (there will be a 15 second warning). Usually, it's best to pick one that's on the opposite end of whichever temple is expected to activate. Then walk them over.
If timed correctly, you should catch the opposing team just as it is preoccupied with battling a temple guardian. The opposing Heroes, who might be worn down from the fight, now have to split their attention between two creatures and the incoming players. That should give you enough time to wipe out the heroes and finish off what's left of the guardians to take the temple for yourself. One especially useful skill is Bribe, which allows you to pay off the mercenaries just as the temples are activating.