Magic diversity

[Twan]

1) I'd say all but one (usually blood)
2) one powerful or several
3) ideally with the level to forge boosters, at least with level 2 if needed for site searches
4) site searching !!! even more than forging, it's the first reason why you need all paths (with an exception for astral and sea nations having multi-searches spells)
5) earth+air for rain of stones, teh overpowered spell (a rare combo you usually only get with tartarians, worth to empower a troll king in air) ; blood + earth for bloodstones is excellent too
6) astral is the terribly overimportant first absolute necessity ; a crappy swamp allowing to recruit an overpriced lizard shaman worth more than the richest farmland if you have no other way to get it