I'll create a complex mathematical expression that combines various LaTeX elements including matrices, integrals, sum notation, fractions, and special symbols.

$$
\begin{align*}
\iiint\limits_{\mathbb{R}^3} &\left(\nabla \times \vec{F}\right) \cdot d\vec{S} = \lim_{n \to \infty} \sum_{k=1}^n \binom{n}{k} \oint_C \vec{F} \cdot d\vec{r} \\[1em]
&= \det\begin{pmatrix} 
\frac{\partial}{\partial x} & \frac{\partial}{\partial y} & \frac{\partial}{\partial z} \\[1em]
\mathbf{i} & \mathbf{j} & \mathbf{k} \\[1em]
F_x & F_y & F_z
\end{pmatrix} + \sqrt[3]{\frac{\displaystyle\int_0^\infty e^{-x^2} dx}{\Gamma\left(\frac{3}{2}\right)}} \\[1em]
&= \left.\frac{d}{dx}\right|_{x=a} \left(\bigcap_{i=1}^{\infty} \bigcup_{j=1}^n \oint_{\partial \Omega} \vec{F} \cdot \hat{n} \, dS\right) \\[1em]
&= \begin{cases}
\displaystyle\sum_{n=0}^{\infty} \frac{(-1)^n}{(2n)!} x^{2n} & \text{if } |x| < \pi \\[1em]
\displaystyle\prod_{k=1}^{\infty} \left(1 + \frac{x^2}{k^2\pi^2}\right) & \text{otherwise}
\end{cases}
\end{align*}
$$

This expression includes:
1. Triple integral with vector calculus
2. Binomial coefficients
3. Line integrals
4. Determinant of a matrix
5. Cube root
6. Gamma function
7. Set theory notation
8. Surface integrals
9. Piecewise functions
10. Infinite series and products
11. Multiple types of brackets and delimiters
12. Vector notation
13. Partial derivatives
14. Special functions (Gamma)
15. Multiple alignment points
16. Vertical spacing adjustments
17. Different sized matrices
18. Conditional statements
19. Complex mathematical operators

Would you like me to make it even more complex or focus on testing specific LaTeX features?