Welcome to the first [Tactical Exploration]. I would like this to be wide open to new ideas on how to use different units even if they aren't utilized heavily at the moment.
Let's explore the Blood Angel Techmarines together. They are definitely an underused unit on the table because of points cost, Elite slot competition, unusual army role, amount of utility versus an enemy may be somewhat unpredictable, etc.
Stats: The Techmarine has the standard Marine line except he has a 2+ save.
Special Rules: They are not independent characters. Although you can run Servitors (without mind-lock) with them. Bolster Defences actually got better considering that cover saves have generally been lightened. Blessing of the Omnissiah is basically the reason for a Techmarine's battlefield existence.
Wargear: Servo-arm- this allows you to fix your vehicles on a 5+ roll. You need to be in base contact and roll to fix during the shooting phase. If fixing a weapon destroyed, it will be able to fire immediately. The Servo-arm allows you an extra close combat attack at Strength 8 Initiative 1 but ignores Armour Saves. That's pretty valuable in a challenge. If you have a servo-harness, you can fix a vehicle on a 4+ roll, get two Servo-arm attacks, and a twin-linked plasma pistol and a flamer that can both be fired in the same shooting phase.
From the Blood Angels FAQ:
“Blessing of the Omnissiah: In each of your Shooting phases,
instead of firing his weapons, a Techmarine may choose to
repair a single friendly vehicle that he is in base contact with or
Q: Can a Techmarine that is in base contact with multiple damaged vehicles attempt to repair them all?
A: No. A Techmarine can only ever make one repair attempt per turn.
If you want your Techmarine to be effective, you have to get those repair rolls chances in your favor.
On the whole, the new edition is friendly to the Blood Angels' version of the Techmarine. He has a nice 2+ save and his shooting repairs are now enacted immediately. The Servo-harness is a nice upgrade although that needs to be balanced by only having one wound.
If you take the Servo-harness, you might as well take a plain Servitor or two as an ablative wound and to help fulfill its main function of battlefield mechanic. Fulfilling this role will require a lot of movement, so despite the increase in power of the Plasma Cannon, it will still be hard to actually get shots off and it can't fire snap shots either. However, you shouldn't receive too much early fire from your opponent as your Techmarine will be lower on their target priority which will allow you to get premium positioning. Use this to your advantage. Remember, the Techmarine doesn't have the option of taking a dedicated transport, so they will have to borrow one. You'll have to think about how he will get around. Will it be on foot or will it be an assault squad razorback with twin-linked assault cannons or maybe twin-linked lascannon?
Your other main choice is then for your Techmarine to become like a Devastator squad. In this instance leave your Techmarine minimally armed to just absorb wounds and load up your servitors with Plasma Cannons to drop tons of damage on your opponent. This unit will serve as a distraction to your opponent because between two and four plasma cannon shots a turn will be hard to ignore. If you want to play more defensively, make sure they have a nice firing lane to where you think the enemy will be advancing into mid-field. If they make it there, they will pay for taking the advantage dearly.
What about unusual choices?
Landraiders- Well you could pack them inside of one, but it would make more sense to follow it in a razorback so you can keep your assaulty units tucked away inside of it instead. You can jump out and still get in base to base to fix it and then embark onto it after. If you have two Land's Raiders then you may want to dump them in quickly and let them zoom ahead first drawing fire.
Techmarine in a razorback with Death Company within a following razorback would be a major distraction to your opponent and allow a greater chance of getting to enemy lines.
Please add any great ideas you've used or seen for Techmarines in the comments.