Given that both of these games are from the same studio (Krafton aka Bluehole), the inevitable question will be, “how does the combat compare between the two?”
TERA’s action combat is definitely much more free form and therefore feels far more faster and dynamic. A:IR’s LoS (line of sight) style of combat where some skills soft lock and others are telegraphed, makes it feel slower and stiffer (for the lack of a better description). Basically, if your target is not registered and you swing your weapon (if melee) or fire off a ranged attack, your character isn’t going to actually be attacking/doing damage to that enemy.
The following shows the LoS reticule where an enemy hasn’t been locked on yet. Keying off skills won’t register any damage. I need to line up the reticule so that it actually locks on (it’s a soft lock because if anything else moves into my line of sight, then the reticule will lock on to that other target).
The following has the monster soft locked.
This doesn’t mean you can attack only one monster at a time. You can sort of group up monsters and tag them especially when you have groups that are in close proximity to each other, soft lock on to one of them and AoE the entire group so long as you have one of them soft locked. But it’s nowhere as fluid feeling as TERA’s free form action combat.
As someone who mains a highly mobile class (Ninja) and also plays most of the other classes casually in TERA, that sheer speed of play style is missing in A:IR. I rolled a Gunslinger and it definitely isn’t as fast paced as the Gunner in TERA (or how mobile/fast paced the cannon shooter was in Devilian).
That isn’t to say the combat in A:IR isn’t impactful; it is when compared to a lot of other MMO’s. The point is that it isn’t as quick paced as TERA. Regardless, it will still be relatively easy for a TERA player to get used to the ground based combat in A:IR.

