How to get more exp?

Does destroying for example a lightning tower give more exp than a skull tower? Do clan boosts, war boosts and pro league boosts give you more exp? How about forging upgrades? And same about troops like ninjas, all defense troops including gargoyles coming out of gargoyle towers, beasts? Does summoning a dragon give you exp? What’s the most exp you can get from a base?

  1. Does destroying for example a lightning tower give more exp than a skull tower?

You can find everything here in the wikia: 

http://royal-revolt-2.wikia.com/wiki/Category:Obstacles

http://royal-revolt-2.wikia.com/wiki/Category:Towers

http://royal-revolt-2.wikia.com/wiki/Category:Units

  1.  Do clan boosts, war boosts and pro league boosts give you more exp?

No, a base gives the same amount of xp with or without elite, war and pro boosts.

3)  How about forging upgrades?

They aren’t counted the forgings you do.

4)  And same about troops like ninjas, all defense troops including gargoyles coming out of gargoyle towers, beasts?

Yes all of them give XP.

5)  Does summoning a dragon give you exp?

No, Dragon can’t be killed ,he is immortal (offense and defense sides) so you can’t gain XP from dragons.

6)  What’s the most exp you can get from a base?

This depends on your XP perks how much high they are. if you have 280% XP you can get 700K XP from monks bases, and 900K XP in mummies bases approximately.

Out of the most a base with many jester boxes can give a good amount of XP for a brief cost time to upgrade to max lvl 7.

For towers Lightning Towers but also the latest Heal Tower gives a very high amount of XP, Basilisk Tower is still unknown.

Answer n°2 is interesting, but in question n°6, KK Star said that necromancer (out of skeletons) gives a lot of XP (see here). Moreover, Flothaboss made an old video about Towers and obstacles XP.