What is the best way to handle those ensnaring spiders? They seem to paralyze my party before I can even fire a shot at times.

Believe it or not Magic Screen and Elemental Shield help a lot.

Either that or just sneak up on them and launch some sort of attack around a corner in round 1 then move in close on round 2 and beat the crap out of them.

Yah. My other solution is to avoid them by being the wrong level for them to show up. Widowmakers and Viles tend to prefer biting if you can close fast enough, but Ensnarers are just tough. If i go into the Caves at all, i go too young for them or not until later. But essentially, since their attack is handled like the Spell Paralyze, any protection high enough in Water generally keeps you out of trouble. (odd that it's not Web...)

Ensnaring spiders are just deadly. In some games I had to avoid then entirely (X-ray), our party wasn't up for it.

Spiders hate fire.

If your characters are finding it tough, tip the scales in your favor with some persistant damage spells like clouds, firestorm, ring of fire etc... that way the spider will still take damage even if many of your characters are paralyzed.

I rarely have much trouble with them, but then again nearly all of my party members each carry 5 Cure Paralysis Powders at all times.