For the curious, here's my summoning log for 30 or so levels (all f2p, dumped all my gems into summons for 40 levels, didn't start logging until later, but only summoned maybe 10 MS before this):

# element unit

1 water high elemental
2 water high elemental
3 wind werewolf
4 fire werewolf
5 fire yeti
6 fire viking
7 water golem
8 wind harpy
9 water living armor
10 water hellhound
11 wind bearman
12* fire nine tails
13 wind golem
14 wind golem
15 wind elemental
16 wind living armor
17 fire viking
18 fire magic archer
19 fire inugami
20 water golem
21 fire werewolf
22 fire mystic witch
23 water fairy
24 fire minotaur
25 wind harpy
26 fire inugami
27 water golem
28 fire grim reaper
29 fire high elemental
30 water inferno
31 fire imp
32 wind magic archer
33 water amazon
34 water basilisk
35 fire serpent
36 fire drunken master
37* fire sylph
38 fire werewolf
39 wind serpent
40 fire high elemental
41 wind martial cat
42* wind phantom thief
43 wind inugami
44 water harpy
45 fire serpent
46 fire grim reaper
47 fire fairy
48* wind golem
49 wind serpent
50 wind minotaur
51 fire golem
52 fire mystic witch
53 water drunken master
54 fire serpent
55 wind warbear
56 fire imp champion
57 water werewolf
58 fire beast hunter
59 fire taoist
60 fire werewolf
61 water beast hunter
62 water amazon
63 wind minotaur
64 fire taoist
65* fire nine tails
66* water ninja
67 water lizardman
68 wind mystic witch
69 wind harpy
70 fire bounty hunter
71 wind minotaur
72 water hellhound
73 fire bounty hunter
74 fire minotaur
75 fire golem
76 wind mystic witch
77* fire nine tails
78 fire salamander
79 fire viking
80 fire grim reaper
81 fire mystic witch
82 wind pixie
83 wind lizardman
84 wind golem
85 fire vagabond
86 water warbear
87 fire living armor
88 water yeti
89* wind imp champion
90* wind martial cat
91 fire taoist
92 wind lizardman
93 wind grim reaper
94 fire beast hunter
95 wind imp champion
96 wind e priest
97 fire magical archer
98 water serpent
99 water beast hunter
100* wind sylph
101* fire samurai
102 wind inferno
103 wind amazon
104 fire imp champion
105 fire drunken master
106 fire golem
107 water harpy
108 water fairy
109 fire golem

110 water werewolf

Stats

total nat 4.....8
total other 4...3
total 4..........11
% 4* 10.09%
% 5* ZERO BABY
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Highest unit counts:
9 golems
6 werewolves
6 serpents
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Highest specific units:
4 fire werewolves
4 wind golems
4 fire golems
3 fire nine tails... :/
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Out of 8 packs, I had 4 in which I pulled 2 4*s.