Epic Seven Wyvern 13 1 Min / 1 Shot Rem
Relatively easier requirements for one shot/1 min but you have to give up 2 really good units to do it. Alternative ways to do it are letting rem kill the first wave with s3 and she can maintain demon mode. Ideally, you can get a good 4.8kish atk counter set on rem which would work in PVP too. Damage is a non-issue, the last attack from rem was 40k+ overkill. Singelica needs 200 ER. The success rate is relatively high, should be a decent bit above 85%, rem ignores ER and gets 4x 50% to def break and aras gets a 50% too.