There is in the "Monster Manual IV" a CR2 creature called Bloodsilk Spider. It has interesting ability to create a web with "vampiric ability". The web drills into ensnared creature, drains their blood (1d4 dmg/rd) and channels it to the spider (it gains temporary hp equal to the damage delt).
The web is blood-red, wet, immune to fire.
The web can be thrown as a net or set as a trap.

Do you think this ability can be added to The Spider combo after some upgrade?