func_tankmortar is an existing brush entity available in (HL2) Half-Life 2 with all versions of Mapbase.

Brush Mortar Turret



KeyValues

- Explosion Radius (radius) <float>
The radius of each shell's explosion. Reflected in its effects as well as its damage. 0 = Default (350)
- Trace Mask (trace_mask) <choices>
The mask to use for when the mortar is tracing attacks from above. Good for when you want the mortar to hit NPCs like striders.