Best farming method would be to stack as much rarity as possible and kill whichever main boss in Merciless you can kill the quickest, or whichever you prefer killing. It really comes down to RNG since some people swear by Merveil kills (like me), while others despise it.
Some of the more common MF gear is: Perandus Blazon, Aurseize, and Goldwyrm.
Eventually you'll have a huge pile of alterations from selling identified rares. You'll want to use those alterations to roll maps the best you can (maze, +pack size, etc). I'd say playing maps would be super important for self-found due to only being able to find some of the better caster uniques in maps only (Andvarius for MF, and Rathpith Globe shield). So for advancing your character, I'd suggest farming main bosses and then maps only when you can roll them efficiently.
I understand you only asked about farming routes, so I won't blame you if you don't read the below text about the spell / build. Just putting out some thoughts.
As for general Ice Spear play, it's a fantastic spell that works well with Crit Damage. This is because of the insanely high increase to crit chance in the second form (600%). Its base damage is a bit low, but due to the crit damage it'll really scale up as you level the gem. If I were to focus on only using ice spear, I'd have a single-target and multi-target version.
ST would be: Ice Spear + Faster Casting + Cold Pen + Inc. Crit. Dam
AoE would be: Ice Spear + LMP + PCoC + Life Leech + Faster Casting
Could either be Life / ES or CI. Would prefer CI after getting gear. You'd need some spells like Frost Wall to keep enemies away, and maybe Cold Snap.
Build would be something like this: http://goo.gl/qj5Pv0
Good luck and keep us posted!
Some of the more common MF gear is: Perandus Blazon, Aurseize, and Goldwyrm.
Eventually you'll have a huge pile of alterations from selling identified rares. You'll want to use those alterations to roll maps the best you can (maze, +pack size, etc). I'd say playing maps would be super important for self-found due to only being able to find some of the better caster uniques in maps only (Andvarius for MF, and Rathpith Globe shield). So for advancing your character, I'd suggest farming main bosses and then maps only when you can roll them efficiently.
I understand you only asked about farming routes, so I won't blame you if you don't read the below text about the spell / build. Just putting out some thoughts.
As for general Ice Spear play, it's a fantastic spell that works well with Crit Damage. This is because of the insanely high increase to crit chance in the second form (600%). Its base damage is a bit low, but due to the crit damage it'll really scale up as you level the gem. If I were to focus on only using ice spear, I'd have a single-target and multi-target version.
ST would be: Ice Spear + Faster Casting + Cold Pen + Inc. Crit. Dam
AoE would be: Ice Spear + LMP + PCoC + Life Leech + Faster Casting
Could either be Life / ES or CI. Would prefer CI after getting gear. You'd need some spells like Frost Wall to keep enemies away, and maybe Cold Snap.
Build would be something like this: http://goo.gl/qj5Pv0
Good luck and keep us posted!