Around 22-25 runs of commander's resolve - 1 niel 1 alissa :P Although around 20 plat spirits. Other silver drops - on 20/1 and 30/1 calliope and eunice at first try.
Update - so after 30 runs still this 2 silvers :P But i did artillery in the swamps 5 times and got 3 silvers :P Sometimes i think that rng is clogged on some maps