I would strongly recommend the use of some Poison Wall Rune, an easy to buy item in any NPC seller in Tibia as a Free Account. I usually use two of them, using one right after I go down the ladder at the front of my character leading to Bibby arena, then I go up the ladder once again and use the rune a second time at my left or right side of my char. This way I get protection from being surrounded from Orc Warlords and can take one by one. Of course, you can tank if you are a knight or even a paladin, but for mages is arguably better to kill a few ones in a close range and then spread some poison wall runes in the camp in order to use it to avoid being hit by the orcs. Watch out, if the orcs get poisoned, they will trespass the poison fields!
Stay near the ladder if you are a new player or are uncertain about the power of your character. At level 80, I believe that any vocation can solo Bibby following my tips!
IMAGE OF THE STRATEGY BEING APPLIED:
When Bibby spawns, thrown at her a Poison Field Rune or a Poison Wall Rune and hit her until she dies. I've made a video explaining the method if you need any more help.