Put most of your runes into Ghost meadow and keep it running.
Leave Lightning strike at one rune. Keep putting points into mental regen (note - mental regen from items does not improve regen - there's a post about this somewhere) and air magic. Even at level one it will take a while to get it under one second. Take trading as soon as its available - try find items with regen spells %, +Combat arts, and magic damage. And try and get a 1H staff with 4 sockets too.
Once you have ghost meadow, points in air magic and meditation, and some regen spells % from gear then assess if you need to eat a rune. And make sure you have magic & spell damage bonuses. LS base damage is pretty low in comparison to FB or ice shards.
Eating a rune gives you a big regen penalty, whereas bonuses from items it is about half iirc.
You can get a Lightning strike rune and socket it into a free socket - you also get the secondary effect (in this case regen spells + 10%)
Make sure to get LL% of 9% from vamp runes. BM is weak. You might find LS on a single target is weak, so don't neglect whatever fire or ice spells you use. Be careful on bosses or champions, let Wilbur take some damage and use yellow potions.
I never used COA when I played, or fire spells - used a Ring of ice build. It was good to bunch up enemies, slow then down. With stoneskin and flameskin I'd maybe make a combo, have some yellow potions ready.
This build is pretty gear dependant - having set items from Mammons treasures and black staffs is a big help. Mammons gives Trading bonuses too.
Never was able to find Shiny Kite Shield, or Laraimmes book.
Adding some extra info and links -
http://www.sacredwiki.org/index.php/Sacred:Blackstaff's_Icy_Invocation
http://www.sacredwiki.org/index.php/Sacred:Mammons_Treasures
http://pctalk.info/Games/Sacred2/Wolfes.Lair/SacredUnderworld/SacredUnderworldHome.htm
Nightwolfes site is really informative.
Also if you haven't played the BM at all its pretty tough as he doesn't have constitution, goblins on the lawn are hella annoying if your regen times are high and the archers in the desert are tough. Life leech from socketing vamp runes helps. And I'd start in Bronze till about Level 12, then move to silver.