28101

Plaintext:
The keyword for the last cipher was ‘pi’. The technique used in this cipher is a Caesar square. It’s probably a bit obvious having a square number of characters in the message. The next one might well be a combination of the techniques used so far.

Encryption method:
Transpotion cipher with 14 columns.

Decrypting method:
It have 196 chars, which is a square number (14's square).

Letter frequencies

e : 26
a : 17
t : 16
i : 16
s : 16
h : 14
r : 12
o : 11
n : 10
u : 8
c : 8
b : 7
q : 4
p : 4
m : 4
f : 4
l : 4
w : 3
d : 3
g : 3
v : 2
y : 2
x : 1
k : 1
z : 0
j : 0

The frequency match that in English. So this is not a substitution cipher.
From the number of characters in the message, it should be a transpotion cipher with 14 columns.