Here’s my suggestion, but there’s a lot of room for creativity:
A Yellow Tank-y stat hero with the ability:
Change all Dark tiles to Light tiles.
All heroes get +95% defense until the start of the opponent’s turn.
Elemental Link Yellow: Gain mana when damaged by light heroes.
This would create a hero that is useful in both defense and titan teams.
What would be cool is a hero that fires like half a tornado where it reshuffles the board and gives your heroes mana for any matches but doesn’t give them the automatic 40% mana the tornado does. Basically a hero that changes a horrible board.
Love it! I was also thinking something like: For two turns any new tiles have a 50% increased change of being X color.
Or how about a hero that changes x random tiles into their color. The special skill could be called “convert”. You can start with 3 tiles then add 1 for every level until you can add 10 tiles of the color at level 8/8.