Purple Patch
Overview
Purple patch is a colloquial term for a pre-Issue 1 update in which the developers increased the difficulty of enemies higher-level than the player. "Purple" refers to the Con System in the game where enemies four or more con levels will have their name appear as purple in the target window. Before the patch was implemented, full groups of heroes were often able to defeat enemies that were ten levels higher than them.
Indirectly, the purple patch reduced the potential teaming pool. Prior to the patch, a character was still reasonably effective against enemies 5 levels higher, and that character could team with characters +/-5 levels above or below him or her. Post-purple patch, characters were practically limited to fighting enemies 2 to 3 levels above them, with 4 being the absolute practical cap.
When contemporary forum-goers talk about the "purple patch", they may be referring to the way player character effectiveness scales against different-level enemies:
There's one more table you'll need, to find the effects of your powers against enemies who are not your level. For this relative level adjustment, simply multiply the effects of your powers by the CombatMod in the table below that corresponds to your level difference. The "Above" column is for [Level] levels above the target, and "Below" is for [Level] levels below the target.
Table 4: COMBAT MODIFIERS Level Above Below Level Above Below 0 1 1 25 3.6 0.01 1 1.11 0.9 26 3.7 0.01 2 1.22 0.8 27 3.8 0.01 3 1.33 0.65 28 3.9 0.01 4 1.44 0.48 29 4 0.01 5 1.55 0.3 30 4.1 0.01 6 1.66 0.15 31 4.2 0.01 7 1.77 0.08 32 4.3 0.01 8 1.88 0.05 33 4.4 0.01 9 2 0.04 34 4.5 0.01 10 2.1 0.03 35 4.6 0.01 11 2.2 0.02 36 4.7 0.01 12 2.3 0.01 37 4.8 0.01 13 2.4 0.01 38 4.9 0.01 14 2.5 0.01 39 5 0.01 15 2.6 0.01 40 5.1 0.01 16 2.7 0.01 41 5.2 0.01 17 2.8 0.01 42 5.3 0.01 18 2.9 0.01 43 5.4 0.01 19 3 0.01 44 5.5 0.01 20 3.1 0.01 45 5.6 0.01 21 3.2 0.01 46 5.7 0.01 22 3.3 0.01 47 5.8 0.01 23 3.4 0.01 48 5.9 0.01 24 3.5 0.01 49 6 0.01