Summoning creatures with more than 3 special powers

I want to create spells to summon beings with over 3 special powers. Companion p.122 lists only a maximum of 3 powers. What would be the cost for, say, 5 powers?

For example, I want a ritual to allow characters to summon something along the lines of a Balor (in ACKS terms, it’ll have 7 special powers).

x3 for 4
x3.66 for 5
x4.33 for 6
x5 for 7