First up, we need to look at offensive damage options, so for a standard terminator squad we're looking at storm bolters, with backup from assault cannons, heavy flamers or cyclone missile launchers. Well that's an easy one really, as the only option that boosts firepower without also removing it is the cyclone missile launcher since it can be fired in addition to the storm bolter. The downside really now is that missiles aren't as useful as they were, and the cyclone is no longer really able to give you a dual function against vehicles (even if you have two!). It does still function fairly well against elite infantry and hordes though, and whilst it doesn't improve the terminators efficiency hugely against either, it does help a bit. The assault cannon is my personal favourite option, terminator shooting is still a bit weak to my mind (ok very weak!) and the extra shots combined with the better AP of the assault cannon adds a nice punch that works against both heavier infantry and hordes. Whatever you do though, don't rely on it rending to get you wounds against elite infantry, so only shoot them if you have no other targets. Finally we have the heavy flamer, and again thanks to its higher strength and AP it works well against heavier infantry and horde armies, the downside being you have to be much closer to do that damage, so close in fact you'll be getting charged if you don't take out your opponent.
The 'tactical' terminators still have one further trick up their sleeves, and that's three S8 AP2 attacks each on the charge, so even some dedicated combat units can struggle to beat them up close and personal, and that many high strength attacks are bound to worry the majority of vehicles in close assault as well
Next up we have the assault version of terminators, as if normal ones weren't bad enough you can either take the slightly defensive option of thunder hammers and storm shields to make them really tough, or give them lightning claws to make sure they strike as early as possible. Clearly these two weapons are intended for different purposes, with lightning claws dishing out high quantities of wounds (4 attacks on the charge with re-rolls to wound) and THSS guys holding up just about anyone.
Despite all this though, terminators are still difficult to work with (at least I seem to struggle) so here are a few tactical thoughts I've had on their use, based on my (bad) experiences of using them and (worse) experiences of facing them.
My latest experience against terminators was to face a death wing list dropping in my face in turn one (after my turn one of course) and all of a sudden being faced with over twenty guys with 2+ saves (when your plasma guns and vindicator gunner can't hit a barn door apparently) was less than fun. Similarly I've played games where a single squad of guardsmen has taken down six of mine in a single round of shooting, so that save can be fragile if you're rolling poorly.
Terminators are no slower than the rest of your army, so this shouldn't affect them, but it really seems to, you just can't afford to have that many points not affecting the game either so deploying them in the right way becomes key. You have three options, buy them a transport, deploy them on foot or keep them in reserve to deep strike.
The first of these is expensive, the only transport options being over 200 points themselves. If you take a transport, you need to make sure that it is going to affect the game too, and that many points invested into one unit, it needs to win you the game.
Second, the footslog. The big issue here is how quickly they can get into a position to affect the game. Running means not shooting, which if you run over 4" you can probably live with, but Sod's law says if you forego your shooting to run, you'll end up going a couple of inches at most, and won't be any better off.
The final option therefore is the deep strike. It more or less guarantees you get into the thick of things right away, but potentially you could only have two turns to play with by the time they arrive.
Of these three, I prefer the deep strike, just, from transport and then footslog. And the reason for that is that generally, a deep striking terminator squad will affect the game outcome. They can land right on an objective late in the game, or they can arrive in amongst the enemy laying waste to their battle line on turn 2, but either way they're making things happen. When I took a full unit of termies footslogging, they spent the first three turns advancing across the board, their firepower being ignored by my opponent while they tried to close on his lines, and the next three turns slogging back as I realised they wouldn't be needed on that side of the table. Rookie error maybe, but that's how much these guys tread the tightrope, in that game they were a complete waste of points, barely killed a thing and attracted very little fire because my opponent had little that could really hurt them.
So what's good for tacticals is double good for assault guys, right?
Well sort of.
The key part as far as I can see to using terminators is to commit. A single unit of five is great, but to really have a game changing effect you need to have numbers too, after all a bad turn of rolling saves, even against lasguns, can see a small unit reduced below an effective level. 15 or 20 deep striking into your lines however, particularly if you can improve your reserve rolls, throws your opponent into disarray. Few armies would actually try to charge terminators thanks to that save and their combat weapons, but four combat squads of five can pin your opponent into place, allowing your other units to move in and secure objectives.
I appreciate this has been a fairly brief tactical post (stream of consciousness might be a better term), but remember, terminators don't have to survive to win you the game, the sacrifice of the entire ultramarines first company allowed the rest of the chapter to manoeuvre into position to drive the tyranids from Macragge. If you have to sacrifice 800-900 points of models to win you a game, you'd take it!