The strike is on target; I’ll need a defence roll.
If you retreat and Dodge, you’ll be trying to roll 12 or less; if you attempt to parry (with a retreat) instead, you’d be rolling vs 11, but it might damage one of the spiders legs if you succeed.
The spider’s legs have a three-yard reach; it’s still far enough back in its web that attempting to close to the one-yard range of your Tulwar is likely to get you entangled. Any movement past your & Nic’s current positions will require a DX roll per hex to avoid getting stuck.