you can just simply change the monster to any custom monster you make...
// Add this in mob_db.txt or mob_db2.txt
// 2990,BLACK_MUSHROOM,Black Mushroom,Black Mushroom,1,99999999,1,3060,2693,1,355,500,72,238,58,9999,33,105,67,9999,10,12,1,8,86,0x128,200,1072,672,672,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
// 2991,RED_MUSHROOM,Red Mushroom,Red Mushroom,1,99999999,1,3060,2693,1,355,500,72,238,58,9999,33,105,67,9999,10,12,1,8,86,0x128,200,1072,672,672,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
// Add this is mob_avail.txt
// 2990,1084
// 2991,1085
just add any custom monster that you think it would be immortal..
of course this can be done through src for better effect....but i kinda lazy to show it....although i already done it before.
yep thanks for rep ~