Speeding you opponent's win condition up by 30|24 hp is well worth slowing that win condition down for 4 turns.
its 4 turns now? i thought the ai used 2 of em in row.. and they stacked.. i guess i missed that.. well maybe.. if you manage to heal 30|24 hp in the stalling..
No, no, the Sos stays for 2 turns, but considering that in 2 turns you don't take damage and heal instead, that slows down the opponent by 4 turns.
Think of an opponent that deal constant damage every turn:
Turn | Your HP |
1 | 100 |
2 | 80 |
3 | 60 |
4 | 40 |
5 | 20 |
6 | 0 |
Without SoS you're dead in 6 turns.
Turn | Your HP |
1 | 100 |
2 | 80 |
3 | 60 |
4 | 40 |
play Shard of Sacrifice |
5 | 60 |
6 | 80 |
end Shard of Sacrifice |
7 | 60 |
8 | 40 |
9 | 20 |
10 | 0 |
And you're dead in 10 turns, 4 turns more than without SoS.Of course damage output tend to grow with turns, and i've not counted the HP lost for the sacrifice, but that will explain the concept.
EDIT: Ninja'd by OldTrees