I really like this idea. It fits the name “heart burst” too. So in practice I’d say:
- Heart burst 160TU (1 use) → 100TU (infinite use, must target a monster charmed or love bitten)
- Life drain 50TU → Love bite 70TU (same move but now allows use of heart burst)
- (Carmilla) remove vigor restriction from heart burst
This would also balance Carmilla nicely, especially given she has dual confident strike.