Throwing multiple splash weapons at once

[Framane]

I've read a lot of threads about doing full-round attack with splash weapons or t
TWF with splash weapons but what about when you don't wanna throw them one after the other but rather in a bunch?
Like take a crate of Alchemist's Fire and throw it in your opponent's face or if they want to tie 10 flasks of Acid together with twig and whatnot. Or simply buy a huge glass container and fill it with dozens of Holy Water flasks?
Surely being drench in Holy Water does more damage then being splashed?
I've been asked that numerous times and by various playgroups (and somehow never been asked about doing a full-round attack with those)
Is there an actual rule for that? If not, how would you play it? I guess I could impose penalty on the attack roll and maybr on the range as well as not simply adding the damage straight. Maybe like every flask beyond the first adds only half damage and gives -1 to the attack roll?

[Lady-J]

set one shrink 500 alchemist fires,ices,electricitys and acids and put it in a back pack set 2 throw said back pack at BBEG step 3 do 500d6 fire cold electric and acid damage to BBEG step 4 cry at the horrible waste of money.

[Cevah]

This would be an improvised weapon. Make one attack. If it hits, they all hit. If it misses, they all miss.

All splash damage is summed up. However, any bonus for splash weapons only adds once.

Use the rules under Special Siege Engine Ammunition for how to run the multi-weapon. It has Alchemical Fire and Liquid Ice as examples.

/cevah

[Brain in a Jar]

There are no rules for stacking together a bunch of Alchemical weapons at once.

The closest thing in RAW is a Hybridization Funnel.

Anything else is a Houserule.

[Cevah]

Here are rules:

PRD

Special Siege Engine Ammunition wrote:

Ammunition Cost Weight

Alchemist's fire .. 200 gp .. 10 lbs.
Liquid ice .. 400 gp .. 20 lbs.

Compare to Alchemical Weapons:

Ranged Weapons .. Price .. Dmg .. Critical .. Range .. Weight .. Type .. Special
Alchemist's fire .. 20 gp .. 1d6 .. ×2 .. 10 ft. .. 1 lb. .. Fire .. Splash
Liquid ice .. 40 gp .. 1d6 .. ×2 .. 10 ft. .. 2 lbs. .. Cold .. Splash

That is for 10x price you get 4x damage on the square and adjacent squares, and 30' splash distance.
Additionally, they get a DC 20 reflex to avoid catching on fire/becoming entangled.

[Framane]

So the maths would look something like this: adding 1d6 per 3 extra vials, having a DC equal to 15 + 1/2 the number of vials and for the splash, 5 ft. + 5 ft./2 vials.
These seem to be reasonanble and not make stacking alchemist's fire broken enough that it's a go to for mass damage. Coupled with the -4 for improvised weapon, I think we have a winner :-)
thanks for the feedback Cevah :-)