diff --git a/scripts/devel/spawn-unit-helper.rb b/scripts/devel/spawn-unit-helper.rb
new file mode 100644
index 000000000..999fe7e45
--- /dev/null
+++ b/scripts/devel/spawn-unit-helper.rb
@@ -0,0 +1,29 @@
+# setup stuff to allow arena creature spawn after a mode change
+
+df.world.arena_spawn.race.clear
+df.world.arena_spawn.caste.clear
+
+df.world.raws.creatures.all.length.times { |r_idx|
+	df.world.raws.creatures.all[r_idx].caste.length.times { |c_idx|
+		df.world.arena_spawn.race << r_idx
+	       	df.world.arena_spawn.caste << c_idx
+	}
+}
+
+df.world.arena_spawn.creature_cnt[df.world.arena_spawn.race.length-1] = 0
+
+puts <<EOS
+Arena spawn data initialized.
+
+Now enter the 'k' menu, change mode using:
+  rb_eval df.gametype = :DWARF_ARENA
+
+spawn creatures ('c' ingame),
+
+revert to game mode using:
+  rb_eval df.gametype = #{df.gametype.inspect}
+
+To convert spawned creatures to livestock, select each one with the 'v' menu, and enter:
+  rb_eval df.unit_find.civ_id = df.ui.civ_id
+
+EOS