As you may or may not be aware the item clear also kills guardians and skeletons, as well as dropped items. This also kills all wither skeletons, strays, and elder guardians
Since the elder guardians don't respawn this can be abused to make ocean monuments incredibly easy to raid (with a little knowledge of how the structure generates).

I think I appreciate the reasoning behind killing these two mobs in particular. Skeletons are popular in grinders and can build up to large numbers, and guardians tend to spawn in huge numbers.

Side note: I would suggest adding cave spiders to the mobs killed by item clear. They are also common xp farms and it's likely to find several spawners next to each other. Meaning they can spawn mobs much faster than skeleton grinders.

Anyway back to the guardians. I'm fairly sure that there is no way to kill guardians and not elder guardians. Instead, I suggest not killing guardians at all during item clear. The reason being that the speed with which they spawn makes it pointless anyway.

Here's a few pics to support this:
Item clear just happened:

Less than 3 minutes later we're back to well over 100 entities

Entities then remained somewhere around 150 until the next item clear

Basically, guardians spawn can spawn fast enough, and the item clears are far enough apart that the number of guardians are only reduced for an ineffectively short period of time. With the exception of the elder guardians.

Let me know what you think.
NJB

Elder guardians aren't killed by the item clear. The reason guardians were added to the item clear is their spawn rates can get quickly out of control. In your picture you have 150ish I've been to bases where there are that many it literally lags my client.

While we can't up the guardian kill time without upsetting too many people it comes as a nice breather to the server every hour.

@Nysic Elder guardians aren't killed by the item clear.

Are you sure? I went to the monument pictured with the intention of getting an Elder Guardian to transport to a lake elsewhere. I didn't kill any of the elder guardians, and they were definitely there where I arrived. The item clear happened, and they were not there any more.
Guardians and elder guardians have the same game ID, the elder part is stored as entity data. Such that /kill @e[type=Guardian] kills both elder and normal guardians.

@Nysic it comes as a nice breather to the server every hour.

Yes, but only for 5-10 minutes out of each hour, after which the numbers are back up again. Is that actuall worth it for the server?

@Synchronous
That's a neat way to do it, it's good to know that it's possible. However, any guardians added to the notElder objective that are unloaded when the kill command runs will not be killed, and will not be removed from the objective, it'll keep adding more guardians that may never be removed, which might be a problem.

@NutjobBob As you may or may not be aware the item clear also kills guardians and skeletons, as well as dropped items. This also kills all wither skeletons, strays, and elder guardians
Since the elder guardians don't respawn this can be abused to make ocean monuments incredibly easy to raid (with a little knowledge of how the structure generates).

I think I appreciate the reasoning behind killing these two mobs in particular. Skeletons are popular in grinders and can build up to large numbers, and guardians tend to spawn in huge numbers.

Side note: I would suggest adding cave spiders to the mobs killed by item clear. They are also common xp farms and it's likely to find several spawners next to each other. Meaning they can spawn mobs much faster than skeleton grinders.

Anyway back to the guardians. I'm fairly sure that there is no way to kill guardians and not elder guardians. Instead, I suggest not killing guardians at all during item clear. The reason being that the speed with which they spawn makes it pointless anyway.

Here's a few pics to support this:
Item clear just happened:

Less than 3 minutes later we're back to well over 100 entities

Entities then remained somewhere around 150 until the next item clear

Basically, guardians spawn can spawn fast enough, and the item clears are far enough apart that the number of guardians are only reduced for an ineffectively short period of time. With the exception of the elder guardians.

Let me know what you think.
NJB

rip fps in the second shot

@jamlbon @NutjobBob this is slightly irrelevant but why were tour transfering the elder guardian

I wanted a fishy for my pond

I never found any elder guardians when I cleared my monument.

Just tested this at a second monument and had an elder guardian disappear right in front of me.
I would imagine this is very easy for admin to reproduce using summon commands if confirmation is needed.
Any chance of this being modified? I was able to easily raid a monument with nothing more than an iron pick and a few blocks, to my mind that shouldn't be possible.

Yeah, just a heads up... I found a monument that had an extremely high amount of guardians-- Gibson cleared it out to fix the mob count and lag.. but now that I've tried to clear it out, I notice the Elder guardians are no longer there...

Then we need to bring tnt...

@Naidae Yeah, just a heads up... I found a monument that had an extremely high amount of guardians-- Gibson cleared it out to fix the mob count and lag.. but now that I've tried to clear it out, I notice the Elder guardians are no longer there...

Yeah when it's cleared by mods in that manner, all entities that are despawnable will do so.

sad day, but its all good ^^ much more thankful that Gibson was able to help the lag problem by killing them off