Although a giant tree, anyone trying to cut it down or burn through this hardwood is going to have a big problem on their hands. Here are the defenses for this tower - none will be known unless each one has been triggered in front of the one trying to disarm them or they have a magic device that can tell the tree's abilities and/or have personally dealt with the tree of life on Endor:
Regeneration - this tree regenerates almsot instantaneously. Any acidic, burning, or magic damage it can't regenerate from will be removed by termites that use the tree as a home so it can properly regenerate. This includes the termites having to die to protect or save the bark.
Detection - the tree will only act if it senses hostile intent; it can only sense hostile intent from those who are also magical or spiritual. If whatever attacking it approaches with no magic it will only defend after being harmed or if it feels violence occurring around it.
Razor leaves/Pine needles - Titans Tree will shoot sharp pine needles to pin down or pierce any enemy that is allusive. It's branches and leaves extend the same circumference as Titan's Tower, but can also shoot outward. So if you're in range you can become a pin needle cushion or suffer through a storm of cuts.
Rock Golems - numerous animated rock monsters scattered around the area that have no skill other than chasing, tackling, and forcibly removing targets from the premises. These can be done away with by one hard shot by anything that can break a rock - hammers recommended. They cannot exit the shade of the tree.
Tree Centuries - growing in front of the front door are four thirteen foot large trees, that will come to life and attack anybody who isn't coming for a polite visit. They carry large wood clubs, but are generally very slow and easy to out maneuver.
Magic field - although not metal the magic aura holding the wood together is very strong, it will take a wrecking ball more than a few tries to break through.
Size - the Titan Tree is thick and big, you'll need a large amount of anything to take it down.
Roots - the root hairs and roots in general can protrude out of the ground through the grass and ensnare targets freely. This is the main mode of defense. Inside the tower vines may also grab at any intruders.
Spores - hallucinogen spores from the grass growing around the trunk, poisonous spores from the plants, and sparkling spores from the canopy/crown that illuminate the area. - also highlights and surrounds invisible, spiritual, and intangible beings.
Sap - if anyone makes it inside the tree the tree will excrete a sap to trap them in areas they are idle in.
Paralysis fumes - if anyone makes it inside the tower holes in the hide of tree may shoot vents of paralyzing puff clouds at targets who inhale them.