Upon teleporting, it will release Gaia Traps, displayed as purple clouds. If the player stands in the Gaia Traps they will be temporarily given the Blindness effect and, longer-lasting, the Wither IV effect; this is twice as strong as the Wither's attack effect, which is only Wither II at best. It is almost unavoidable when dashing after the Gaia Guardian to step into one of these traps, so keep some regeneration potions and/or Golden Apples ticking.
Hostile pixies are summoned at random intervals, attacking the player.
The Gaia Guardian will also occasionally lift the player high in the air, paralyzing them in place, then dropping them to suffer fall damage. The best way to avoid this is by staying on top of the Gaia Guardian and attacking it before it has the chance. It is also immune to most projectiles; a good sword is critical.
Finally, when the Gaia Guardian gets to 25% HP it will make itself invulnerable, fly to a corner of the arena, and channel the power of the pylons in the ritual to spawn hordes of hostile mobs. Zombies, skeletons, wither skeletons, witches, and spiders are all some of the enemies it can create. This phase lasts about 45 seconds to 1 minute; concluding this, it will teleport to another location and repeat it's initial phase.
The Lexica Botania will show how to perform the ritual to the exact letter, including the set-up of the pylons. It also highly recommends that the player wear full, enchanted Elementium Armor when battling the guardian, since player-friendly Pixies have a high chance to spawn, and will aid you in defeating the boss.