DND_Reborn
The High Aldwin
Ok, back from lunch. So, if you want to have a discussion (and not just argue)...
If you mostly do dungeon-crawl, then the party starting the fight first depends enormously on how successful you are in infiltrating the dungeon (complex, castle, etc.) and how well the DM runs the "reality" of the location. IME too many DMs treat encounters almost like islands, where one has little if any impact on the other. Once the PCs fail to move to the next area successfully without alerting the entire complex (in a fashion dependent on the scenario of the adventure, of course), the PCs can often expect to be "encountered" as often as they do the encountering. Wandering monsters (if used, it is old-school for many games IME) will more than often initiate the fight.
During travel, random encounters are nearly always initiated by the monsters, but this also depends a lot on the scene, what the encounter is, and how the DM sets it up.
If the PCs start the fight, they usually have only one point of entry, but often need a martial to watch the rear because very often the enemy will move to flank and attack from behind if possible. While many monsters are not very intelligent, the average INT for anything CR 1/2 or higher is 10, and it rises with CR. So, with the exception of super-low CR creatures (many are beasts and such), most foes WILL be smart enough to employ tactics that suite them best in defeating the party. I'm not saying those tactics have to be brilliant or anything, but flanking and rear attacks are not hard concepts when you have numbers.
Given that most parties have 4 PCs, in general if you want an encounter to be any real challenge at all, CR monsters half the level or lower of the PCs will at least match their number, of often outnumber them. Even BBEG encounters will have minions to support the BBEG by harassing fringe party members when the front-liners engage. FWIW, as DM, I also try to have my encounters be a mixture of CRs (if it makes sense to do so), and have smaller CR minions in larger numbers because with bounded accuracy they can make a difference.
At any rate, casters in the rear is a mistake more often than not, they should be center of the party, or they are subject to all kinds of nastiness. Depending on the encounter set-up, even then they aren't necessarily "safe" by any means compared to the martials. More intelligent foes will attack casters with range, numbers, flanking, or whatever. If martials are engaged, they have to disengage to help the caster or wait until they are otherwise free to do so. Your "rear-guard" might be a ranged martial or mobile one who can move up if it is safe to leave the casters behind.
This depends greatly on the style of game you are running IMO.I would be interested to see how the party tactics actually interferes with your statistics. In our games, about half the fights are started by the PCs, so you can bet that they are making sure that the casters are at the back when this happens.
If you mostly do dungeon-crawl, then the party starting the fight first depends enormously on how successful you are in infiltrating the dungeon (complex, castle, etc.) and how well the DM runs the "reality" of the location. IME too many DMs treat encounters almost like islands, where one has little if any impact on the other. Once the PCs fail to move to the next area successfully without alerting the entire complex (in a fashion dependent on the scenario of the adventure, of course), the PCs can often expect to be "encountered" as often as they do the encountering. Wandering monsters (if used, it is old-school for many games IME) will more than often initiate the fight.
During travel, random encounters are nearly always initiated by the monsters, but this also depends a lot on the scene, what the encounter is, and how the DM sets it up.
If the PCs start the fight, they usually have only one point of entry, but often need a martial to watch the rear because very often the enemy will move to flank and attack from behind if possible. While many monsters are not very intelligent, the average INT for anything CR 1/2 or higher is 10, and it rises with CR. So, with the exception of super-low CR creatures (many are beasts and such), most foes WILL be smart enough to employ tactics that suite them best in defeating the party. I'm not saying those tactics have to be brilliant or anything, but flanking and rear attacks are not hard concepts when you have numbers.
Given that most parties have 4 PCs, in general if you want an encounter to be any real challenge at all, CR monsters half the level or lower of the PCs will at least match their number, of often outnumber them. Even BBEG encounters will have minions to support the BBEG by harassing fringe party members when the front-liners engage. FWIW, as DM, I also try to have my encounters be a mixture of CRs (if it makes sense to do so), and have smaller CR minions in larger numbers because with bounded accuracy they can make a difference.
At any rate, casters in the rear is a mistake more often than not, they should be center of the party, or they are subject to all kinds of nastiness. Depending on the encounter set-up, even then they aren't necessarily "safe" by any means compared to the martials. More intelligent foes will attack casters with range, numbers, flanking, or whatever. If martials are engaged, they have to disengage to help the caster or wait until they are otherwise free to do so. Your "rear-guard" might be a ranged martial or mobile one who can move up if it is safe to leave the casters behind.