Dynamic Multiplier for Sacrifice and other costs

currently it might be done via SVars, but i would like a more dynamic approach for Sacrifice Info.

* Like `Jadar, Ghoulcaller of Nephalia` would make decayed creature more likely to be sacrificed to other effects
* `Oni-Cult Anvil` makes Artifacts more likely to be sacrificed doing your turn.

The best way would be if the AI could get that info from the Triggers alone, especially for `triggers only once` like the Anvil. But i don't think AI is intelligent enough for this.

See #362 for cleanup of the SVars via timestamp.