Search for the 'skill_unitsetting' function in skill.c, locate the case for HT_LANDMINE and change the target to BCT_ALL.
E.g. before:
...
case HT_SHOCKWAVE:
val1=skilllv*15+10;
case HT_SANDMAN:
case MA_SANDMAN:
case HT_CLAYMORETRAP:
case HT_SKIDTRAP:
case MA_SKIDTRAP:
case HT_LANDMINE:
case MA_LANDMINE:
case HT_ANKLESNARE:
case HT_FLASHER:
...
case RA_ICEBOUNDTRAP:
if( map_flag_gvg(src->m) || map[src->m].flag.battleground )
limit *= 4; // longer trap times in WOE [celest]
if( battle_config.vs_traps_bctall && map_flag_vs(src->m) && (src->type&battle_config.vs_traps_bctall) )
target = BCT_ALL;
break;
After:
...
case HT_SHOCKWAVE:
val1=skilllv*15+10;
case HT_SANDMAN:
case MA_SANDMAN:
case HT_CLAYMORETRAP:
case HT_SKIDTRAP:
case MA_SKIDTRAP:
case HT_LANDMINE:
case MA_LANDMINE:
case HT_ANKLESNARE:
case HT_FLASHER:
...
case RA_ICEBOUNDTRAP:
if( map_flag_gvg(src->m) || map[src->m].flag.battleground )
limit *= 4; // longer trap times in WOE [celest]
if(skillid == HT_LANDMINE || skillid = MA_LANDMINE || battle_config.vs_traps_bctall && map_flag_vs(src->m) && (src->type&battle_config.vs_traps_bctall) )
target = BCT_ALL;
break;