4/5 stars. An unsung and undersung unit.
Background.
Do you remember the movie "Aliens"? The special edition? They deployed some of these beasts and they stopped so many aliens it was embarrassing. Then they ran out of ammo. And things got more interesting. There's no real difference here except that they don't run out of ammo!
I actually have a real soft spot for Tarantulas in Horus Heresy and I may be over-rating them.
Strengths.
Fundamentally these units are static guns with a low armour profile that shoots reactive shots (interceptor, overwatch, and the special automated fire reaction here).
Automated fire is simple enough. If something ends their move within 48 inches you shoot at it as a zero-cost reaction. But it does rely on movement which might be an issue sometimes. However, you can offset this due to Infiltrate (9) and set up some commanding overlapping fire lanes if you wanted to. They're also very expendable!
Weaknesses.
Two automated heavy bolters for 45 points is a good deal overall. Particularly at BS=4 which is a significant improvement on second edition. However, the AP=10 is an issue and they will be wiped out prompted with a bit of return fire. So treat them as they are: cheap and cheerful, but deadly in numbers.
Builds.
4 Tarantulas (90 points - i.e., 2 slots).
Four lots of heavy bolt guns to saturate your enemies advancing corridors. This is actually okay in comparison to the cost of a heavy support squad.
2 Tarantulas with lascannons (85 points).
Longer range and harder hitting.
2 Tarantulas with Melta Arrays (95 points)
Very short range, but hard hitting. Use wisely with infiltrate. Not highly recommended overall.
2 Tarantulas with Hyperios Missile Launchers (75 points).
Your ground to air interceptors.
I actually wouldn't bother with the Orias Frag Missiles due to one use only. And only if I had lots of Volkite would I consider the Culverin option.


