I think, one "problem" of the wand of monstersummoning is, that you can summon lots of monsters. This makes most fights very easy, especially when you are in Baldurs Gate, have 50k gp and by just 4 or 5 wands. This has been fixed a little bit in BG2, there you can only summon 5 monsters at a time, thus taking much of the power of monstersummoning.
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