Exodus Knife

[Antronach]

I see nothing stating the door is indestructible...

 

[xxXEliteXxx]

Use a portal ritual to go someplace safe.

Use another Exodus Knife to extend the time if necessary.

If an extra dimensional space or portal is placed within another extra dimensional space or portal, a rift to the Astral Plane is torn in the space: the knives and/or players are sucked into the void and forever lost. (DMG 248)

 

[Savage Wombat]

Good heavens, they've cut open a portal back to 2010!

 

[the Jester]

Sounds to me like much of the problem boils down to allowing readied actions outside of actual initiative.

Do that and you're just asking for trouble, IMHO.

 

[Derren]

What you need to do is discuss this with your players and ask them to tone it down, rather than trying to start a readied-action arms race with them (which you will ultimately win because you're the DM and can just say rocks fall, everyone dies)...
Most long-time gamers who've seen the effects of trying to abuse readied actions have a gentleman's agreement in their game to not get stupid with them.

Its useless to ask someone to not use his best tactic. That only leads to frustration.
Either let the enemies fiend a way to deal with this or nerf it.

 

[Dice4Hire]

To me this gets into the social aspects of the game, the social contract, if you will.

At most tables, and mine for sure, we agree not to abuse things and the DM agrees not to abuse players. It is just not fun on either side of the screen in the end. Sure, figuring out a great tactic and using it for a few encounters is fine, but then it needs to stop.

This is especially true if the players are abusing a tactic (in this case readied actions) that the DM could equally abuse. I imagine the 'clever' players would be far less satisfied if the DM started using the same tactics against them.