Tieni conto per varragoth che boast non puoi attivarlo se lo metti per terra con kalia. La stessa cosa vale per ogni istanza tipo "se ha attaccato in questo turno" o "quando attacca":
Merely being put on to the Battlefield attacking does not mean you have attacked this turn. So, Boast can't be activated.
508.4. If a creature is put onto the battlefield attacking, its controller chooses which defending player or which planeswalker a defending player controls it’s attacking as it enters the battlefield (unless the effect that put it onto the battlefield specifies what it’s attacking). Similarly, if an effect states that a creature is attacking, its controller chooses which defending player or which planeswalker a defending player controls it’s attacking it becomes attacking (unless the effect has already specified). Such creatures are “attacking” but, for the purposes of trigger events and effects, they never “attacked.”