Motivated by recent constructions and barriers in secret sharing, we study multislice functions. These functions, parametrized by a width parameter $w$, take the value 0 on inputs of Hamming weight below a base value $k$, 1 on inputs of weight above $k+w$, and are monotone in between.
We first investigate formulas over multislice gates, which generalize the formulas over slices model (Applebaum et al., TOCT 2026). We prove that, although multislices compute complicated functions, they do not help in computing the worst-case function when $w\ll n$; that is, there is an explicit monotone function such that for every $w$, every formula over multislice gates of width $w$ that computes it, regardless of its depth and gate fan-in, has size $2^{\Omega\left(n/((w+1)\log^2 n)\right)}$.
Our lower bound is based on a randomized Karchmer-Wigderson protocol for multislices that can be amortized across the formula.

As a complementary result, we show how to realize multislices using slice gates, i.e., multislice gates of width 0; the construction uses a simple peeling recursion. Consequently, every width-$w$ multislice on $n$ variables has a formula over slice gates of size at most $2n^{w+1}$ and depth $(w+1)$. The same construction allows to compute multislices with small monotone real formulas and circuits, two models introduced by Pudl\'ak (J. Symb. Log., 1997) in the context of proof complexity.
This result also has an application to secret sharing: it yields, for sufficiently long secrets, multilinear secret-sharing schemes for width-$w$ multislices with maximal information ratio $n^{O(w+1)}$, which is polynomial for every fixed $w$.

In addition, we prove that an explicit access structure requires shares of size $2^{\Omega(n)}$ in every secret-sharing scheme from a family of schemes that captures all currently known constructions for general access structures with share size $2^{cn+o(n)}$, for $c<1$. Our proof goes through an exponential lower bound on the size of formulas over so-called CDS gates and ideal linear gates.