Shadowverse

Take Isabel, as I suggested for map leaders. Cost is 4, with enhancement it's 10. Stats are 2-2. Without enhancement, it turns a random or selected follower/amulet into a sigil. With enhancement, it turns everything on both players' boards into sigils. Only another "grime-loving" unit will be grateful.

Thankfully, the developers haven't gone completely crazy and made runecraft even more overpowered than it already is. At least, I hope they haven't.

Added 7 hours 54 minutes later

I managed to get 100 wins with Havoc in ranked play in three days (Saturday doesn't count, I barely played), but my rank didn't increase at all. Huge thanks to the "Dashas" and "cockroaches" (and to a lesser extent, the "Sahams," as they started showing up less frequently).
My highest score was 700 points, but then a series of "Dashas" and "cockroaches" appeared, and everything dropped to zero.

Added 5 minutes later
Now I'll try to earn the banner with Tsubaki for the "grime-loving" knight.