I am level 20 but the store wont allow me to purchase tier 3 runes.
The runes are lvl 20+ which means over lvl 20.
As so: lvl 21 and higher
20+ does not mean 21 and over, it means 20 and over. The inability to purchase runes at level 20 is a bug.
This is a known issue that will be addressed with the next patch. Right now you can resolve this by leveling to 21.
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