Do Plant Growth and Thorny Entanglement work together?

Question

Thorny Entanglement (Advanced Class Guide pg. 196)

School transmutation; Level druid 3, hunter 3, ranger 3, shaman 3, witch 3

Casting Casting Time 1 standard action

Components V, S, DF

Effect Range long (400 ft. + 40 ft./level)Area plants in a 40-ft.-radius spread

Duration 1 min./level (D)

Description: This spell functions as entangle, except the plants also grow thorns and can fling them up to 15 feet. Any creature that moves within 15 feet of the spell’s area is attacked once on its turn by the animated plants. The plants use your caster level as their base attack bonus and add your spellcasting ability score modifier (Intelligence for witches; Wisdom for druids, rangers, and shamans) to the attack roll. A volley of thorns counts as a thrown weapon and deals 2d6 points of piercing damage on a successful hit. A creature that enters the spell’s area or ends its turn there automatically takes 2d6 points of piercing damage.

and...

Plant Growth (Core Rulebook pg. 322)

School transmutation; Level druid 3, hunter 3, ranger 3

Casting Casting Time 1 standard action

Components V, S, DF Effect Range see text Target or Area see text

Duration instantaneous Saving Throw none; Spell Resistance no Description Plant growth has different effects depending on the version chosen.

Overgrowth: This effect causes normal vegetation (grasses, briars, bushes, creepers, thistles, trees, vines, and so on) within long range (400 feet + 40 feet per caster level) to become thick and overgrown. The plants entwine to form a thicket or jungle that creatures must hack or force a way through. Speed drops to 5 feet, or 10 feet for Large or larger creatures. The area must have brush and trees in it for this spell to take effect. If this spell is cast on an area that is already affected by any spell or effect that enhances plants, such as entangle or wall of thorns, any DC involved with these spells is increased by 4. This bonus is granted for 1 day after the casting of plant growth.

At your option, the area can be a 100-foot-radius circle, a 150-foot-radius semicircle, or a 200-foot-radius quarter circle.

If a Druid cast those 2 spell in the same area, does it mean that the save DC for Thorny Entanglement will raise by 4 AND the area inside it and around will reduce the movement of all character to 5 feet, meaning that even if the character pass their saving throw to not get entangled they would only be able to move 5 feet inside the Thorny 40 foot radios!?

Answer 1

Yeah, that's exactly how these spells are supposed to work.

But before you call it overpowered, let them try it out at least once. It uses up both the Druid's 3rd level spell slots (assuming they have enough Wis to even have 2 slots) and requires 2 actions to set up, while creatures will start trying to leave the entangled area after the first one already. Also, most combats don't last more than 3-4 rounds, so by the time this effect is fully active, the battle is probably half over anyway. And it only works outside.

It might be very powerful, but that'd be pretty situational, which is generally fine; let the Druid shine in those situations. In the average dungeon, this combo doesn't work anyway, in the average outside combat it probably won't deal more damage than 2 Fireballs, and the Fireballs will grow even more powerful in the coming few levels, while this combo doesn't.