Ballista
From Dungeon Defenders 2 Wiki
out dated information with damage numbers see link
Ballista  
Fires a piercing projectile that deals Physical Damage in a line. Deals less damage to each enemy hit after the first.  
Tower Statistics  

A Burst Tower that attacks multiple targets in a straight line in a very long range. Deals more damage the longer the bolt travels, dealing maximum damage at long range.
Can be enhanced by the Powerful Spears spec, giving Ballista projectiles a chance to deal full damage to all targets pierced for the next 4 seconds.
Attribute  Tier One  Tier Two  Tier Three  Tier Four  Tier Five 

Attack Damage Defense Power (x) 
12x  16.8x  21.6x  26.4x  31.2x 
Crit Damage Defense Crit Damage (x) 
2x  2.8x  3.6x  4.4x  5.2x 
Max Health Defense Health (x) 
14x  17.5x  21x  24.5x  28x 
Attack Range Special 
35  36.74  38.5  40.25  42 