Sometime you get in over your head and need to retreat. But running away is harder in 4e than in 1e.
In 1e you had a simple rule for breaking off from melee: monster gets a free swing at the fleeing character (DMG p. 70). The procedures for dealing with pursuit, on the other hand, took nearly two pages of small font, with different subsystems for pursuit outdoors and pursuit underground. We never used them, and I’m not going to parse them out for the purposes of this article. It was more of a chase mechanic than a disengaging mechanic, and despite the attempt to systemize it, it boiled down to ad hoc adjudication.
In 4e disengaging is similar to 1e because of opportunity attacks (although it is less of an issue if you still have an action point). However, a significant complicating factor is the individual initiative mechanic. First edition generally assumed group initiative (individual initiative was possible but Gygax warned against it as too complicated – and then proceeded to outline even more complicated rules respecting initiative for creatures with multiple attacks and different speed factors – see DMG p. 62-3).
When you have group initiative, everyone gets to flee at the same time without interruption by the monsters – opportunity attacks excepted. With individual initiative, on the other hand, when the PCs high in the initiative flee, they often leave holes in the line that allow team monster to move to block the retreat of the remaining PCs, or to focus fire upon them. This especially sucks when the team defender would be the first to retreat.
The answer to this in 4e is to delay your turn until all of the PCs are acting on the same initiative count. Then they can retreat in a coordinated fashion.
The objective, on the first round of retreat, is to get far enough away from team monster that they cannot attack you on a move-charge. If you are outside the range that the monsters can reach in one move action and one charge action, this means if they want to attack you they can only take a single move action in the round, and will have to use ranged attacks. Many monsters don’t have ranged attacks, or have weak ranged attacks, so this should reduce the number and quality of attacks you need to deal with, while making you more likely to outdistance the monsters.
Getting outside of charge range likely means making a double-move, even if you have to risk the opportunity attack. Even if you are at low hit points, if you risk the opportunity attack you are only dead on a hit; whereas not risking the opportunity attack means you are almost certainly dead once team monster gets the initiative and everyone gets a swing.
Getting outside of charge range probably also means running (if you are fighting orcs it definitely means running). Don’t be afraid to risk granting combat advantage due to the run. If you run and grant +2 to team monster’s attacks, but team monster has to run to catch up, and suffers a -5 penalty on its attacks, you are better off.
If you are moving 14 squares per turn at a run (going at the slowest PC’s pace), and the monsters are moving 5 or 6 squares per turn so they can stop and shoot at you, you will quickly outpace them. It only take a round or two to get out of range of most missile and magical ranged attacks; javelin and bow attacks take a little longer if you are outdoors, but there are likely to be fewer of them, and the archers were probably in the back row anyway.
Don’t forget your unspent action points, which can be used to attack in a retreat round (attacks that slow, immobilize, blind, daze or stun can be handy), or by leaders to grant extra movement. Keeping caltrops and tanglefoot bags on hand can be handy for the non-casters. Also don’t forget your minor actions if you have any that can help; for example, unused healing powers can shore up characters who are in danger of being taken out by an opportunity attack or a ranged attack. The four-sided caltrops from Dragon 417 can also be deployed as a minor action.
If there are PCs who are unconscious, slowed, immobilized, or otherwise unable to retreat effectively, you have a choice to make. A healthy defender might be able to hold off team monster while the afflicted attempt saving throws or limp away; an unhealthy defender might also be able to do that if you are willing to sacrifice the defender to save the others. Sometimes you just can’t save everybody, and free PCs at least have an opportunity to rescue or bargain for captive PCs.
If you are in an area with choke points and terrain that limits the effectiveness of enemy missile fire (like the winding passages of a dungeon), then it is possible to run a fighting retreat against a significantly superior enemy. This usually means shoring up your defender, who provides cover to everyone else, and moving into positions where the enemy can’t bring many attacks to bear but the PCs can. Winding passages work well for this.
If you get to a door, close it. Bar it, lock it or spike it if you can. In 1e adventurers carried iron spikes for various purposes; this was one of them. Remember Hold Portal is only a standard action to cast, and anyone in the party can donate the healing surge if the Ritual Caster is running low.
Do that and you might just avoid a TPK. And avoid tempting your GM to cheat to keep you alive.