A tree farm made with nothing but Botania. Credit: /u/prybulets

Magic, Tech. Naturally.

Botania is a tech mod themed around natural magic. Gameplay is centered around creating magical flowers and devices using Mana, the power of the earth.

Botania is fully playable as a standalone mod (and is designed as such), but it functions just well in conjunction with other mods.

The mod focuses on automation, but without elements that make it feel grindy-- systems can be thought out and designed, rather than built blindly from blueprints in JEI or a wiki.

Botania's design philosophy:
No pipes, wires, etc-- they're boring and overdone;
No GUIs-- interact with everything in-world;
No numbers-- players shouldn't try to minmax everything;
Keep all resources as renewable as possible;
Provide pleasing visuals, despite using only two different particle effects.

Botania's goals:
Break the mold of mods being means to ends-- be engaging in gameplay as well as in rewards;
Deliver fun and balanced gameplay without forcing players to grind;
Incentivize sandbox gameplay and allow players to create fun contraptions;
Create an overall immersive experience.
Download Botania

Still not convinced? Check out some videos.

Riskable and Jansey's tutorials are a great way to see what you can achieve with the mod.
If you'd prefer a more traditional assessment of Botania, consider Direwolf20's spotlights. (Note: these might be a bit outdated.)
Looking for a Let's Play? Check out Vanhal's LP of Garden of Glass (an optional botania skyblock mode).