How did the wolves knock the Giant prone? They don't have the Pounce ability. They have Pack Tactics, which gives them advantage when an ally is adjacent to the target.
Quoting from the SRD:
SRD said:
Keen Hearing and Smell. The wolf has advantage on
Wisdom (Perception) checks that rely on hearing or
smell.
Pack Tactics. The wolf has advantage on attack rolls
against a creature if at least one of the wolf’s allies is
within 5 feet of the creature and the ally isn’t
incapacitated.
Actions
Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one
target. Hit: 7 (2d4 + 2) piercing damage. If the target is
a creature, it must succeed on a DC 11 Strength saving
throw or be knocked prone.
It's worth mentioning, the Fire Giant could sacrifice his ability to attack, and take the Disengage action and move right through the wolves as if they were water, which is what he should do.
Really? That would have saved him 35 points of damage, at the cost of both of his attacks. It's basically giving all 20+ enemy creatures a free round of attacks on him. If his mindset is so defensive already, why is he even launching an attack instead of negotiating?
Also, why is only the Paladin in range? Are all of the casters staying at maximum range?(120 feet for Wall of Force), if so, how did the wolves make it into combat with the Giants in order to provoke opportunity attacks, as their speed is only 40 and it would have taken them two rounds to reach the Giants? Did the caster conjure them at the maximum range, aren't the giants in some kind of den or something?
The paladin is the only one in range because the PCs know how to count, and the Paladin deliberately advanced into range in the OP to present himself as a target. Assume a den about the size of a high school gymnasium, 100' x 60'. Giants start out initially lounging somewhere near the center, some near the walls (I rolled randomly to see how many could be caught by the Wall of Force, got 2) PCs enter from one of the doors. Call it 50' to 65' away from the giants respectively, but it would turn out the same even if it were 30' or 90' initially, since the PCs have the surprise round and know how to count movement.
BTW, you don't have to stay within 120' to maintain a Wall of Force, merely to cast it. The giants don't know this but the PCs bardlock and necrolock have ranges of 240' and 600' respectively on their Eldritch Blasts, so they have lots of range to play with.
Assuming, at huge "tall" size a Fire Giant is 2x2x4, then all four of them, resting comfortably, would need at least double that amount of horizontal room, so a square-footage area of a minimum of 20x20, assuming they have some space in there I would imagine their den is something along the lines of 40x40. And they're completely trapped by wolves? That's just unbelievable. Even if the wolves were set side-by-side, forming a barrier across the room, it would take 8 of them to do so, so at best you'd have a two-wolf-thick line. If a fire giant charged that line he'd make it look like a trail of ants in his path.
Conjure Animals has a range of 60'. I may have been too generous to the giants--I had assumed that only the wolves which won initiative got opportunity attacks on the giant(s), but in real play there's no reason the bardlock couldn't just summon them right on top of the giants before ducking back around the corner. Then all sixteen wolves would have gotten opportunity attacks on round #2 (house rule: animals conjured during combat count as surprised on the round they are summoned, since they didn't know they were about to be summoned) instead of only eight of them.
You're right that they don't block the giant's movement because they're not big enough, but that's not what's going on here. It's not completely trapped, it's just surrounded in 8 of the 10 surrounding squares by wolves. The other 2 squares are taken up by giant furniture.
BTW, the bardlock in this scenario specified his priorities as 1.) cobras, 2.) giant owls, 3.) wolves, 4.) draft horses. I rolled randomly and he got his #3 pick, wolves, instead of something better.
So what I'm really saying is that I'm questioning your math. This situation seems very, very fuzzy.
I'm not sure how your AD&D initiative and speed factors are working in here, but it feels like there's something else heavily working in favor of the party.
Partly luck--the giants probably should have hit the Paladin more than they did. I was surprised to see four whiffs in a row--I was expecting him to take something more like 40 points of damage, since he hadn't even activated a Blur spell or anything. Partly it's just the overwhelming force advantage of outnumbering the giants 10:1. Partly it's the power of recon and Shadow Monks with Pass Without Trace. None of that is really relevant to what I'm really interested in though, which is: how badly-outclassed does a typical giant (i.e. human Enworlder) have to be before he realizes it and surrenders without making the PCs tear him to shreds first? I don't want to lean on my own intuition here because I think I am not average enough.
So far, discussion seems to indicate that any given Fire Giant is probably not going to believe he's outclassed while he still has half his HP left. Maybe the old heuristic of "fight until half HP, or until half your comrades have surrendered or died" is valid after all.
