So, Bloodmages...

[Naoya]

The supposed "ideal case" would be to never touch a bloodpool until lategame, for maximum burst against the bosses.
Below vicious this tends to overdo it; and on vicious and above, there's a good chance the already weaker early on top of the harder early will strangle you if you get unlucky, so in some situations its not quite as ideal. Using a Bloodpool or two early on for higher level kills is fine, as long as you don't overdo it - Just make sure its worth it.

So the lesson of Bloodmage Silver was that you should jump to meele combat lategame? Huh, never figured. I mean, certainly, 20% sanguine got to be good for physical approaches, but it always seemed a hassle to me to boost the damage of the BM and turn him into a brawler, especially since his spellcaster approach works so well. Use B2P early, drink potions late, drink bloodpools and use B2P anyway, regardless if you have Blackspace or not. Burning, corrosion, and bonus fireball also go long ways in this.

A funny sideeffect of B2P is that it actually increases my exploration efficiency; I tend to waste blackspace, often overexploring the map and wasting it with failed attempts on bringing down stronger monsters. B2P helps me somewhat with the exploration, and works as a spiking tool to boot.