Piercers, especially ones at high levels are most easily dealt with from far away due to their slow speed. If possible, avoid using a physical weapon on them. The HIKS 3100 for example is perfect against Piercers.
On the Map meltdown, one must be very wary of Piercers coming up, due to the incredibly tight areas around the map.
Other information Edit
Appearance wise, a Piercer is similar to a stalker, but more of a dark grey and lacking horns. Piercers do not have hands: Instead, they have pick-axe like claws.
A Nightmarish Apex Piercer is an incredibly dangerous thing, as it actually gains huge physical resistance and has sizable toxic resistance as well (compared to basic ones at least). Additionally, it ignores 28% of armor; these can demolish even tanks.
Extremely dangerous with Extra strong, Dark minion, poisoned limbs, berserk, extra fast (they are slow), and chitinous hide.