"I knew this would be bad" Zork climbs on top of his horse to get a better aim as he shoots through or above the gate.He tells his dogs to aide Durgan and his gal.
Sessativa reacts immediately with an Armor spell and ensures everyone's awake. She pulls out her quarterstaff to keep them at bay as she moves behind Durgan. She tries to recall anything she's read about these foes.
Durgan first casts a Bless spell (+1 attack and damage to all allies, including dogs maybe?). Then he moves in to attack with his mace.
Out of Character: Yes bless work on all allies in the area so the dogs will attack with a plus one to hit as will everyone else I will add a plus one to your attack rolls [Txtrpg].
Are the attack rolls for Durgan only any special actions or attacks from [Sessativa]?
Round one Zork hits for 6 damage as the four spiders get close. One bites a dog for 6 damage you need to roll a d20 for a saving throw on the dog. You hear Sessativa tell everyone these spiders should be poisonous.
Round two Zork hits for 4 damage Durgan misses. Another dog gets bit for 3 damage plus a d20 to save.
Round three Zork misses but Durgan gets a good hit in causing 10 damage. The spiders miss but You hear Sessativa say there are three more coming down off the walls.
Round four Zork hits the first one for 2 points damage. Durgan hits for 8 damage killing one.
A spider bits a dog for 5 damage. You pick one and then make a d20 roll.
Need more attack rolls.
"Alright!," Durgan breathes out. "Time to test out this thing. Stand back!" He hold his helmet steady, thinking of fire coalescing into a ball. He aims as best he can at the wall the three spiders are coming down and says "BLINK!" trying to send forth a fireball. He tries to avoid hitting the dogs while getting the most spiders.
He charges into combat after that while Sessativa grabs a burning log from the campfire and moves to the gate, checking if more are coming from the other side of the wall.
Out of Character: Secretly, he wouldn't mind so much if one dog got caught in the fire as long as he could hit an extra spider. He would be willing to pay Zork for a replacement.
I'm not sure precisely how many d6 on the fireball, the spell description mentions wands, staves and scrolls. I assume it's minimum level (5) but I added a sixth roll if not.
And I can't believe I forgot my own +1 to attack and damage, which should be affecting Zork's rolls too.
Finally, I hope that you don't mind me pointing out that you described two climbing up the wall, and suddenly we're fighting four. I know they must have come over as well, but they seemed to just appear.
Edited: iCon on 15th Mar, 2016 - 1:19pm
Hearing the yelps of his dogs while they fight makes Zork angry. He fires even more arrows with slurs added to each one directed at the spiders. When he hears Durgan he shouts, "Watch out for my dogs!"
Out of Character: The spiders are coming down the walls from the top down towards you. They are on top of the walls where no one was able to see them. Yes there are more joining into the battle.
Durgan your fireballs do a total of 6d6 damage. Thus 21 damage to the spiders and a couple dogs unless saving throws are made. Make sure to mark off one fire opal.
Zork I need two d20 for your dogs save vs poison and now 2d20 for two of your dogs to save vs fire.