Is your party outnumbered? Low on armour? Confined to a narrow passage? No worries, mate! Just roll out this camouflaged welcome mat, and let your foes take care of themselves!

Shape a piece of ground into hard spikes. A creature walking on the spikes takes 2d4 piercing damage for every 1.5 m / 5 ft it moves.

The diminutive die in that description might look laughable at first glance, but consider how large the spiked area is: 40 ft diameter, meaning 16d4 or an average of 40 damage to anything that crosses its full width. All those tetra-dice sure are pointy!

The area is wider than a typical humanoid's movement per turn, so most things without wings won't have time to do much after crossing it.

On top of that:

The spikes are difficult terrain, halving a creature's movement speed.

So, while waiting for the baddies to slog through the brambles, you can pass the time with target practice on their ranged-attack buddies.

What's that you say? Your visitors somehow made it across, and are now breathing down your neck and twice as pissed off? Perfect! Now's the time to practice your thunderwave, or favorite knock-back ability, or turn undead if the neighbours are necrotic, or just give them a good old fashioned shove, and let them enjoy your garden tour all over again.

Wait a minute! You're facing a threat of higher intelligence and refined poise, and they stopped before stepping on your grass? What a great time for your druid to yoink them out of their comfort zone with a thorn whip, or (if you earned it as a reward) try out Sorrow's similar spell.

Did your barbarian charge in before you could seed the field? Ask her to toss a body or two onto the flower bed while they're still standing. They make great compost!

In short, wizards and sorcerers might love to talk about their fireballs, but with this horticultural marvel, my bard has more fun. All natural, certified organic, and (as a level 2 spell) cheap and easy.

Happy plowing!