I was thoroughly disappointed with Biomes o Plenty when, after meticulously moving all my Gregtech mid-level hardware to a remote tropical island for its nearby volcanoes, that they were only single source blocks on the peaks! What a rip.
Are there any volcano mods that do what I need? Namely, place a surface-accessible central lava chamber? OR a mod that allows you to drain below Bedrock (which is presumably supposed to be the mantle)?