On the other hand,one might not like the other items with the same focus effect, so last blood becomes an easy choice for that focus. Melee effects have 2% shielding vs 2% spellshield on focus effects, and accuracy instead of avoidance. Those might affect your choices also. I used to aim for a lot of focus effects on last blood, but ended up with just getting extended buffs (primarily for WoT) and detrimental mana preservation (had to choose something). Will end up with 5 pieces of GM/LB, and taking fero parry and dodge for the other effects. Just use whatever effects you have difficulties covering with other items. Without a magelo to look at, that's the best advice I can give
