The arguments for using
Sacred Spawnings
in yourLizardmen Army...
1) Usually your enemy will not know if a unit or character is sacred until in combat with it. It can come as a nasty suprise to your enemy to discover that your Temple Guard actually strike first and have 3 attacks not 2 !
2) Most of the spawnings are good value for money, especially the unit spawnings and the...
Blessed Mark of the Old Ones
(for 35 pts one character can re-roll up to D3 dice rolls (D6's) that directly affect the character during the battle).There are however some massive drawbacks...
1) They mess with your special and rare unit choices ! If you give a core Saurus unit a sacred spawning they become a special unit, give them 2 spawnings and they become a rare unit !
2) There is a 'hidden' cost. If you give a unit spawnings you must given any characters joining that unit the same spawnings.
All of the spawnings are quite useful. The blessed mark of the old ones is a potential battle winner depending on what rolls you choose to use it for.
Spawnings are really too expensive for units in a 2000 pt game because of the special and/or rare unit choices you lose (you can still take them for characters though). If you do choose to take them, they should be used sparingly and with a particular tactical objective in small 2000 pts games.
Note: In 3000pt + games you have a lot more room to experiment with spawnings and you should.