You can dislodge low number stuck at the bottom by leaving the same low number over the stuck one, getting rid of the numbers between the two, and once the top one have fallen down to adjacent the bottom one you add them.
The strength of the shot is in direct proportion to the distance between the square position and the place of your click. Just shoot near to the border of the screen for stronger shot.
The endless mode consists of repeated positions of elements. Learn how to go through each of the 'scenarios' and you can get a high score.
I found the trio of rogues powerful. With focus on Stealth (to get the 'dummy' skill), Attack (to get the last skill and jump) and One-hand weapon (dagger) along with passive skills increasing damage and 'red' god, the rogues have increadible dps with critical hits reaching 497, and are able to get behind the front line and eliminate mages and archers. Receiving damage is reduced by the 'dummy' skill, invisibility and dodging that can be developed after the first three traits.
(Normal mode was easy with them; I haven't tried hard mode)
 "Get 10"){kind=icon}
 "Fling"){kind=icon}
 "Dinogen Arena"){kind=icon}
 "Wondrous Lands"){kind=icon}
 "Combatants"){kind=icon}