This SIGNI's [Constant]ability will trigger and activate even when she attacks the level 4 SIGNI, or when she is attacked by a level 4 SIGNI.
If Lævateinn is attacked by a level 4 SIGNI with more power than Lævateinn, Lævateinn will not be banished as a result of the battle.
This SIGNI has both Arm and WeaponSIGNIclasses. Where applicable, both of her classes will apply for abilities.
When Lævateinn attacks Code Anti Vimana, Lævateinn will be banished before entering battle.
Code Anti Vimana's [Constant] ability will trigger immediately at the declaration of an attack, before Lævateinn's [Constant] ability (which triggers during battle) can trigger.
Therefore, if Lævateinn declares an attack, and your opponent's Vimana is across Lævateinn, and Vimana has a higher power than Lævateinn, Lævateinn will be immediately banished by Vimana's [Constant] ability before Lævateinn enters battle.