Area of Effect spell similar to the pillar spells and fungus trap.
Damage ignores armour and is applied repeatedly, with damage depending on the power of the cast.
Offensive spell resistance
Many damaging spells and grant the targeted player a resistance effect. This duration of this effect is based on how much damage is done, and will reduce all further damage on the target from the same spell.
The maximum duration of resistance various depending on the spell, and the reduction scales linearly from that mark. For example, if you have 1 minute of resistance remaining and the spell has a maximum resistance duration of 2 minutes, you will receive 50% normal damage from a further cast of that spell.
Tentacles has a maximum resistance duration of 3 minutes.