Echo shard instantly refreshes the cooldown of the last-used ability
allowing it to be used again immediately
This grants a charge if used on the Mini Turret, allowing you to immediately drop two turrets down, or drop two Spectral Walls down on someone
The power to generate extra turret charges out of thin air and shorten the cycle time of turret charges lets it supplant other cooldown items and charge items very effectively, though because the cooldown of Echo Shard is affected by Superior Cooldown, it is still useful to build both (and Rapid Refresh) for even more turret spam
The power of Echo Shard also comes with using Spectral Wall to drop two walls in short sequence
This can be used to trap people in tight quarters, block off an entire lane, or simply to spam more walls for the useful stun and damage buff
It's also useful for correcting wall mistakes - like trying to stop someone from running away, but you drop the spectral wall short and so your target is on the far side of the wall
Removing Spectral walls is not possible if Spectral Wall is off cooldown, as pressing "3" will cast Spectral Wall, but Spectral walls will "travel" through other spectral walls, letting you drop a spectral wall on the other side of the stunned enemy to sandwich them, very useful for trapping people in buildings or subways.Another useful thing to remember is that you actually remove spectral walls one by one, starting from the oldest, letting you correct the trap by dropping the first wall and exposing the enemy to you, while leaving the second correct wall in place
Medicinal Specter buffs and healing do not stack, so there's no point on using Echo Shard on Medicinal Specter unless you need to reduce the CD or increase the effective area of effect
This has niche benefits in increasing turret/creep survivability while split pushing multiple lanes, but it's generally better to use Echo Shard to drop another turret down.