This is why I said the zigs and zags of the combat are not a factor to consider. We can all dream up an infinite number of possible scenarios to negate what the other guy said. For example, what if the monsters out number the PCs, or are attacking from the flank, or can fly, or all have bows, or all have darts (perhaps in their tails like Manticore) or have move rates that enable them to outrun PCs? What if the caster's retreat path is barred? The list of "circumstances" is infinite and any hypothetical pro could be countered by a hypothetical con and vice versa.
I agree. But in the game the pros and cons are not hypothetical so the zigs and zags do
matter. The fact that there are infinite situations where a caster can be shut down, and infinite situations where a caster can't be shut down, and infinite situations where it could go either way means that the rule isn't abusable, and not really an issue. Anyway as a fair GM there should be a mixture of situations. The situations where the caster can't use spells are the ones where the rest of the team should step up, and make space.
If you use individual initiative (the norm in the rules as written) then the likelihood of that increases with the size of the parties involved.
The rules as written say the GM may make single rolls for groups of identical monsters at his or her option. If that doesn't make it part of the norm then I don't know what does.
None of this requires knowing what the other side is doing. When your (or the monster's) initiative number is called, if the caster has not gone yet, then you (or the monster) simply say, "I'm attacking the caster on his number (even though you don't know what it is).
If someone waits for an event that doesn't happen then their turn is wasted. That's the risk taken by delaying.
If the caster hasn't gone yet then the enemy still has choices:
1) Delay for the opportunity of disrupting a spell and risk wasting a turn
2) Make an attack/progress to a goal and risk having the caster use a spell.
If the caster gets to act, but the enemies haven't acted yet (whether initiative was won or not might be unknown to the caster) then the choices are:
1) Cast a spell and risk having it disrupted,
2) Delay until all enemies have acted and risk getting attacked and possibly killed, or wasting a turn because someone else delayed.
3) Do something else that brings them closer to their goal, and risk getting attacked by someone who delayed.
Everyone still has these choices whether you use group initiative or not, but knowing what the other's actions will be is
If Choice A is objectively better than Choice B, then there is no choice. The cost of a wasted turn should not be underestimated
. That's what makes these choices, and choices are what make games like this fun.
The practical impact of this is that it's extremely difficult for Magic Users to use spells when they are within range of enemy weapons (a common event in this game). A short bow can fire out to 150 whereas a Magic User needs to be 10th level for his lightening bolt to have that same range. In the ubiquitous "dungeon" setting, 50 feet is a long way; a foe in light armor can run that distance to strike with a melee weapon in the same round. So getting beyond the range of enemy weapons is no easy task.
Is the party not using a choke point? Is the caster not near the back? Are the fighter, thief, and any other characters between them unable to get parting shots on the enemy running through their ranks? There are plenty of ways to get out of range, and plenty of disincentives to running straight at the caster, not the least of which is making a fun game. People don't always act optimally especially under stress, this should be reflected in their roles not just their rolls.
This thread started because you found a specific situation where the caster cannot be disrupted even on low initiative. Now we've found a specific situation where they cannot act except on high initiative. Most situations will be somewhere in between so it's not really a problem. Regardless the focus should be on creating situations with interesting choices. Without choice the game is really just a subpar story time.
Call me Joe. Mr. Munkey is my father.