Goosebumps Horrorland Series Books 1 - 18 Collection Box Set by R.L. Stine:

Titles in this set:

1) Revenge of the Living 

2) Creep of the Deep 

3) Monster Blood for Breakfast 

4) The Scream of the Haunted Mask 

5) Dr Maniac VS Robby Schwartz 

6) Who's Your Mummy?, 

7) My Friends Call Me Monster 

8) Say Cheese - And Die Screaming 

9) Welcome to Camp Slither 

10) Help! We Have Strange Powers! 

11) Escape From Horrorland 

12) The Streets of Panic Park 

13) When the Ghost Dog Howls 

14) Little Shop of Hamsters 

15) Heads, You Lose 

16) Weirdo Halloween 

17) Wizard of Ooze 

18) Slappy New Year!