I take this idea from wheN I'm playing Zombe Mod 3 in CSO NST, if you stand in 5 second, you will regen with 200 hp

so have fun with it

, this is some cvar in plugin.
PHP Code:
zp_zombie_heal_enable 1 // plugin toogle, 1 is enable, 2 is disable
zp_zombie_time 5 // the time you must to wait for regen
zp_zombie_heal_amount 200 // amount of heal when regen
p/s: Sorry, My Eng is veryvery bad...