Normal Summoning condition

This card cannot be Normal Summoned or Set.
Blanket statement, in no circumstances can the card either be Set face-down, or Normal Summoned/Tribute Summoned. This is included on all "Special Summon-only" cards.

This card cannot be Normal Summoned.
Slightly different to the first condition, a monster can still be Set face-down with this limitation.

This card cannot be Normal Summoned or Set except by...
This is much like the first two examples, but this time, it allows the card to be Normal Summoned or Set by one effect or conditions only, and cannot be Normal Summoned without fulfilling this requirement. This is typically used to prevent the card from being Normal Summoned by Mausoleum of the Emperor. However, as with that card, any Summon performed this way will not be considered a Tribute Summon, even if tributing monsters is specified by the effect.

If you Tribute Summon this card by Tributing 3 monsters...
These card grant you an option to Tribute 3 monsters for the Tribute Summon to activate an effect, such as Gilford the Lightning and Moisture Creature. You can, however, still Tribute Summon this card by offering two Tributes. You cannot use Mausoleum of the Emperor to pay 3000 Life Points to summon these monsters in order to activate their effect(s).