To give you an example:
in NS, lerk isn't very useful on it's own. But it can do the Primal Scream to boost offense and Umbra for defence/to help advancing through long corridors, or something. Lerk isn't strong enough to attack alone, but is good support.
Similar for gorge. Let's forget about base building ability for a moment - gorge can heal wounded teammates and place webs, which do have tactical importance.
Now back to Tremulous. It is hard to observe (match is often basically over at that point), but according to documentation Tyrant has a healing aura similar to that of a Booster. So what ? It doesn't really matter, because a single tyrant can easily kill several unsuspecting/inexperienced marines. And at least damage a base, especially destroy a turret or two, clearing the way for the others. At the moment, tyrants are pretty much self-sufficient, just like rambomedics are in Wolf:ET. "Healing aura for lesser aliens" doesn't matter.
Granger isn't very useful on anything against base building. Possibly to shoot jetpackers down, but it's not easy as it sounds because most tremulous maps have lots of bottlenecks, and much fewer vents than NS.Which is hard to understand, because the most dangerous aliens are very big and wouldn't be able to use a vent anyway; little or no damage to balance.
What am I about to say ? Well, anytime you advance to shoot a jetpacker down, he expects you and already is facing your direction. Even worse, you may easily be spammed with Lucifer by someone who can't see or hear you.
Another thing that puzzles me is: why is Basilisk so crippled against Battlesuit ? I mean, it's probably ok that poison becomes useless, but "restricts ability to turn" not working on battlesuit is an overkill. . Basilisk already has fairly low rate of fire(melee attack), and quite low damage. It takes about five hits to kill light armor marine. With halway competent marines, it's an eternity, plenty of time for another marine to kill you. Now battlesuits are much tougher than regular marines, and require much more time to kill from behind... I mean, WOULD require, because as soon as you grab him, he simply turns and kills you. Even if he can't, chances are he has Lucifer gun and can kill you with splash damage.
Making Baslilisk's hold ability work the same on light and heavy armor would be beneficial for gameplay and would promote teamplay. A basilisk would still need a ridiculous amount of time to kill a battlesuit alone, so you'd need a teammate to help finish him. Please, at least make basilisks good at assasination and ambushes. Even dretches can bring Battlesuit down, why not a basilisk, already stripped of poison ?
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The state of Tremulous teamplay isn't too good when compared to NS or Wolf:ET. There's another tweak it could use, a good idea suggested by someone else. Make medikits unlimited to heal others, but impossible to heal yourself with. It would further encourage teamwork.
My suggested addition is that it shouldn't work within, say, 5-10 seconds since taking damage, so you can't heal faster that Hive/Basilisk deals damage, for example. I'd say make it non-combat item.