You can catch two of the ones that you can see, if you’re quick on the draw.
All right, I cast sleep at them.
I’ve got the ranged attacks, so I shall try to take out any frogs trying to harm me. Self-preservation is a good instinct to have. 
Though if I do see a wounded frog or a weakened one, I’ll try to be an opportunist and use my Magic Missile on the occasion, but I’d rather save that shot for when it’s needed and depend on my darts in the meantime if I can.
“I’m digging fighting in Super Slow-Mo it’s almost like time has stopped.”
(Sorry - have to go out for the evening - will update tomorrow.)
Here goes:
The frogs react more quickly than you were expecting. They all have gigantic tongues which flicker out with startling speed. Melon, Frodo, appleciders and Ishtar all find themselves caught. The frogs are trying to pull you off the path into the deeper water and mud.
Melon tries a panicky swat with his mace on the tongue that is stuck to him but doesn’t hit it effectively. Hoopy casts sleep as per the plan and puts out the two frogs attacking Frodo who, however, was interrupted before he could start his spell this round. appleciders braces himself against the pull of the tongue and hits it, raising a bloody gash - the frog lets go with an offended croak and hops closer, snapping its absurdly large teeth menacingly. Ishtar accurately nails the frog at the other end of the tongue holding him with two darts out of three, dropping the annoying amphibian; but the dart that misses lands in the water and disappears for ever with a mocking gurgle. Oredigger77 needs more reach and belts his axe in favour of the halberd - it’s very hard to switch places on this narrow path. Wolverine hits fresh air with his mace. Autolycus makes a wild swipe with his sword, menacing nothing, and Trotman looses off a couple of arrows without effect.
The remaining frogs continue to try to pull you into the swamp. Another tongue hits Melon and the two frogs already attached carry on pulling. Trotman looses off twice at the one on appleciders, wounding it. Oredigger77 stretches out as far as he can but cannot reach far enough to help now that Frodo’s frogs have been dealt with. appleciders and Frodo can’t reach, but Autolycus knocks one of the tongues off Melon - just as well, as the Pastafarian didn’t seem to be managing anything very effective. Ishtar hangs onto his remaining darts.
Disheartened by the ferocity of the resistance, the remaining frogs hop off into the swamp. There are two sleeping ones just out of poking range, but you could get an unopposed round of missile fire into them if you wish (any hit on them will wake them up, and Hoopy knows that his spell will wear off in about three more minutes anyway). With very great care, you could try to salvage two of Ishtar’s darts which are stuck in a dead frog.
I check to make sure everyone is ok/no one below half health.
“Just like a good roof, we built a solid defense that the storm of frogs could not prevail against.”
I had the most miraculous hit of all. I found fresh air in a swamp."
Ishtar shall carefully try to salvage his darts. If anyone wants me to take the free shot at one of the frogs, I certainly can do so, but only if the others deem it the right thing to do. And I’d rather stay a bit back from the actually messiness of… killing it. So if others would like to sneak up on the frog to perhaps stab it… in the back. I can certainly aid from a distance with the magic Missile.
Just say the word, and I’ll go for it.
I’ll draw my bow, nock an arrow, and prepare to shoot the sleeping frogs in synch with the other ranged weapons in the group.
I’m not sure if I can reach, but I say do it. I like fire.
Melon has yet to hit a single thing in the entire game.
You overcooked your noodles. You need to be more al dente.
A coordinated volley of missile fire (don’t forget that you carry a sling for occasions like this, Autolycus) sees the two remaining frogs dispatched to the Happy Spawning Grounds with no need for the Magic Missile. Ishtar manages to retrieve his darts without quite getting stuck, but it’s closer than he likes and entails getting seriously muddy.
No-one is badly hurt and the passage of the marshes resumes.
Melon, being low level sucks - there isn’t anything in the game that you even have much more than a 50-50 chance of hitting at the moment. And you haven’t been in many fights yet.
“I guess it ain’t easy being green” quips Autolycus as he runs his fingers over the sling he had forgotten in his back pocket.
Melon rubs frog muck off of himself and gives a grim nod to the party members.
“Why are we doing this, again?”
“Beats farming”
“You’re right. We could be beet farming.”
The expedition continues. Once or twice you feel a prickly sensation at the back of your neck, as though you were being watched, but when you stop and look around you see nothing except perhaps a flicker of movement in the reeds a chain or two away. There is no sign of any more frogs, nor anything else trying to make a meal out of you other than a tedious succession of nearly-invisible insects.
Towards mid-afternoon the party reaches firmer ground. Trotman says there is about half a mile to go. There may be undesirables about and he is willing to leave it to your judgment as to whether you go on now or wait, and how you intend to go about your business. He doesn’t mind shooting things if there is need, but he was sent as a guide, not a scout or a man-at-arms. Besides, you will need him for the return trip.
“We might as well press on standing still won’t accomplish anything anyhow. Besides I’d like to get away from these damn bugs. We don’t have anyone who is capable of being a scout so we might as well stay in a tight group with the mages in the middle and just try and spot trouble before it’s on top of us.”
“Waiting does nothing except make us vulnerable during the night. I say we press on. I’ll guard our flank. One fighter in front, one in back. Melon can twiddle his thumbs wherever.”