@Lonis: That's not what I meant. Thanks for the hint which I can use to gain the journey amulets "beat 60 waves on any field" and "beat 90 waves on any field", I'll try that ;)
What I meant was the challenges for challenge amulets, like those on fields C7, G10, H11, K9 and M10 which say "Reach hundred waves beaten on C7" and so on. Can I do those without premium? Also, the other challenges on fields C11, K12, L9 and M7 which say "kill at least 7000 monsters"... how to do so without premium?