I'm using Disguise Self from Mask of the Shapeshifter here, this character is actually a Wood Half-Elf, so slightly more movement speed. I was not using Crusher's Ring and I couldn't use Longstrider with my build, but I do use the Mobile Feat. I use "Boots of Speed" from the Underdark in Act 1 almost always with any character I do not spec into Rogue. They allow you to Dash on a bonus action. The Illithid power "Fly" lets you move farther. By regenerating, I'm taking it that you mean the stacks of "Unstoppable" kept regenerating? They regenerate every round until you kill all of the cultists that are part of the ritual (the ones with Sanctuary on, on the outer circle of the arena). I use a combination of Magic Missile scrolls here and Spirit Guardians to remove Unstoppable stacks once the cultists are defeated. Unstoppable reduces all damage to 1 and removes a stack of it.