The sniper can only place one at a time. It stays where its place and starts shooting at nearby enemies. Be carful, it doesn't care if you or another friendly unit is standing between it and the enemy, it will fire anyway. It also blows up when attacked by enemies, after a time period, or after a certain amount of shots. You can also jump on top of them If you place one down, the AI will always throw a gernade at it.
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