How to cross lava?

You have the right idea... just keep stacking.

Bug pellets, best FIre resist gear you have***, all resist ring, fire resist ring, probably the best one though is the pyromancy flash sweat.

Additionally, make sure you're embered for the higher HP. If you have the attunement slots/faith make sure you equip and cast a HP regen spell prior to entering the lava, and be ready to chug those flasks.

Another suggestion was to equip (and raise) a high fire resist shield prior to entering the lava, this will help mitigate additional damage until you lower it for your first heals/rolls.

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*** while keeping your equip load < 70%, but preferably < 30% for the best rolls.