Buried Spikes
"A booby trap that will spike the enemy forces from below and impale them! Place these near your building or design your walls to tunnel attacking units towards these invisible death traps."
These traps can kill multiple enemies if they are walking in packs.You need City Center level 2 to unlock the Buried Spikes. The higher your City Center level the more Buried Spikes you can have, up to a maximum of 60 traps. Buried Spikes are good defense against low health dps mercenaries like the Bedouin Brute and the Persian Hashishin. Flying units do not trigger Buried Spikes. Only ground units and Blacksmith items trigger Buried Spikes except the Persian Sapper unless the sapper surfaces on one of these traps. After that a trap is triggered you have to re-arm the trap again at the cost of some resources..
Buried Spikes Explained
