AWKWARD ZOMBIE

Okay, I'll go with Madican's suggestion. No wounds or anything are added to the disguise, I want to look like the guy did when he went into the forest. I stash my items under a bush or something and cover them with leaves, and I ask the party to keep an eye on them. I only take my cheddar and my holy symbol with me, which I stash under the chestpiece of the disguise so that they're hidden.

Then, I jog to the gate and when I'm in clear hearing distance of the sentries I shout "Hey, I've found something in the forest! Quickly, open the gate!"


Also, in response to Krom I say, "Hold on just a bit chap, I'm going to try and save us the trouble of chopping down the gate, you can fullfil your bloodlust soon enough".

4 (2 human 2 elf) of the guards head down to open the gate, and upon opening it, "Alright, what's so important you need us to... what happened to Billsby!?" He looks at the not-dead-yet corpse of the other guard.

OW, you are on the top of the wall, invisible. You can see into the fort, and most of the structures. There is a stable with slimes in it on the opposite side of the fort, you know, just chillin', doing slime stuff. In the front corners are some stairs leading up and down from the wall to ground level. In the back are some small buildings, 2 with guards in front of, two without. You can walk from the wall to the top of those buildings. In the middle there is another building, with spikes jutting out the sides and torches lit in front even though it's the daytime. It has a rat king in front of it, you know, just chillin', doing rat king stuff. The side of the wall you are on is apparently over a target range, nothing special about it. As for the part of the wall you are on now, to your left is the front, where all the front guards have all just gone downstairs.

"Shit," said Shinsa, readying her sword. "Krom? Smash."

She bursts from her hiding space and charges at the group of four, pointing her sword aloft as she does so to unleash what was quickly becoming her favorite trick.

Roll: 13+2=15

Due to the clear skies, your failure chance kicks in, and no lightning comes out. However, the sword does start crackling a little and won't stop, but can't be heard beneath the sheath. The guards don't notice you.

"YES!"
Krom leaps out and charges the nearest bad guy with his sword.
Power attack 2!
Roll: 19. Confirm Crit: 19(!?).
damage (5+2+7)X2. 28 damage.

I don't really care to roll for crit confirmation, too much extra rolling. So yes, you crit. BUT! You weren't with the others when they were killing the other elf and disguising Syobon as one. And your spot check to see through the disguise was a one, so you believe he is one of them. So I will now randomly roll to see which of the "five" guards you hit. And, I don't know how to tell you Syo, but you're hit. Luckily, I checked your sheet and it doesn't actually do enough to kill you! Or even knock you out!
"Quick, everyone inside, you too Sugar Jr.!", one says to you. Your elf disguisee's name was apparently Sugar Jr. And also they still haven't noticed you're not him, maybe the fact that you've just been attacked instead of one of them helped.

I'm assuming since they haven't noticed a charging paladin that this is going to be a surprise attack. Does that mean a crit? SMITE EVIL.

Roll= 11+8=19
Damage= 8+6=14. If a crit, then 28 damage.

Wait, sorry, I misread your post, I thought you were just lightninging them from the bushes, not charging. But I won't retroactively make them see you, it's too late for that.
Not a natural 19 so not a crit, but it still hits. Anyway, though your spot check also failed to discern which one is Blanche, you didn't hit him, and instead get one of the human guards. He is knocked below 0 and falls over.
Anyway, the remaining guards begin running in and hold an action for whom they believe to be Sugar Jr. to get in to shut the portcullis. And it is Blanche's turn now.

(Okay, did not expect to almost get killed off by my own party)

I take a 5-foot step out of Krom's threat range and cast Sanctuary on myself.
I try to motion Krom and Shinsa that it's me and that they should go smash the other guys, without the guards at the gate noticing.
(Let's hope Sugar Jr had levels in Cleric, this might start to look suspicious.)

I'm going to get to the portcullis controls as fast as my stumpy legs can carry me through non-guard infested territory, find some cover inside sneak attack range of the guards there, and take a shot at the one with his hands on the controls before he can throw them if possible. If I can't get there soon enough I'll keep hidden and make my way close to the controls to try and get them open if the guards clear out.

Through interpretive dance, you manage to inform Krom and Shinsa that you are actually you, while also preventing the guards from realizing you aren't Sugar Jr. They also fail to realize you cast anything.

OW, through a series of excellent jumps and tumbles, you make it to the ground relatively unharmed (2 damage) and close enough to shoot. You make your hide check for when you turn visible again. You recognize which guard is Blanche and will not accidentally shoot him even if you weren't aiming for a particular one. You may roll to sneak attack the guard at the lever.

Into the breach, then. Attack: 15+9=24, Damage: 4+6+1=11

I'll make ready to fire another shot at any of the guards who go for the lever or the slime pens. From where I am can I see if I can somehow jam the mechanism so it won't operate easily but also won't send the portcullis crashing down?

You manage to shoot the one at the lever and he goes down. The guards who readied their actions for when the gate go down panic, the human tries to get out his horn to sound the other guards but drops it, the elf guard stops to command the slime to attack. The slime gets ready for its turn. You can wait until your next turn to try shooting the portcullis controls.
Next up is Krom.

Krom: charge in and attack the next guard (Who isn't one of your teammates in disguise.)
Power attack 2!
Roll 8+9+2-2=17 Damage: 1+3+4+7=15

The guard scrambling for the signalling horn gets axed. These bargain bin minions just don't hold up, and he goes down.
The slime makes it's move, and targets Shinsa with a body slam, (15+3) and hits for a total of 10 damage (g slam, 4 acid). It's attempted grapple fails miserably at a nat1, so it grapples itself. And hold up a moment, the monster manual lists none of the ooze as having acid immunity so... it actually hurts itself with its constrict damage (7).
I guess it's Shinsa's turn now.