[Taqwus]

You need to find the sites that offer mages with multiple randoms or higher paths, then.

Some paths are easier to leverage than others. Death is among the easiest, probably; a death-2 mage can forge a 10-gem Skull Staff, making him death-3, which allows a 20-gem Skull Helmet. A death-3 mage can also summon a D3U3 Mound Fiend; give the Fiend a Skull Staff and Skull Helmet and he's D5U3. That, IIRC, might suffice for a Demilich, which is inherently D4 and thus goes to D6 w/ those two boosters. An additional point of D can be found through the death/blood artifact book, or subbing the Sceptre of Dark Regency for the staff (+3, for 2 points net gain), or a sorcery or wizardry booster. But once you reach D2, add a staff, and D3 mages can summon more D3 mages or D1/?1/?1 mages plus build boosters to make 'em D4 or D2/?1/?1. You might also be able to find D2 indy mages; I can't remember right now whether Necromancers are D1 or D2. Any D1 mage at least can cast Dark Knowledge to find the death sites, as well.

Nature is also good for versatility; Lamias for sorcery, faerie queens for branching into air, witches and similar for small numbers of randoms. It's more expensive to chain-summon and boost than death, however. If you're going to rainbow, you might as well guarantee some access (pretender or national) to death or nature for the branching.

Compare to Air, which is relatively expensive to boost (the helmet and bag each require an air-3 mage and 20 gems, the staves of elemental mastery require A3/E3 and 20/20 gems, there's an artifact book as well, and a RoSorcery won't help) and isn't nearly as good for chain-summoning (only 3 air queens, and you need A5). It's a very nasty combat school school, 'tho, especially for SCs (2E/2A Tartarians cloud-trapezing and mistforming, oh my!). You can find indy 2A mages (amazons, IIRC) but 3A is a bit trickier. Auspex is also harder to cast than Dark Knowledge, requiring 3 levels rather than 1.