Gerontius provides healing items, and the occasional (and much-appreciated) Yggdrasil
essence. Barbella delivers magic cannons, which are the only way to damage the Dragonlord
when he's far away. Use them when the game queries, "How can you attack the Dragonlord from so
far away?" Your cannons won't have much of a shelf life. After one or two hits, the Dragonlord will destroy them.
Rollo appears and provides Cantlin shields. When the game poses the question, "How can you block the Dragonlord's
bite?" place a Cantlin shield in front of, and facing, the Dragonlord. Biting the shield stuns him long enough for you to get
in a few hits with a melee weapon.
Magnus provides stone blocks, which get put to use when the game prompts you to build a tower of blocks to climb
to safety. Don't bother with a tower. Hold the Aim Below/Look Down button, jump, and while still in the air, set a block
directly underneath yourself. Repeat the process in rapid succession to get above the Dragon lord's sweeping breath
attack with time to spare.