Battling Smaug[]
Getting to Smaug isn't hard since the 2 campaigns you need to get through only require 2 key fragments per map. Necromancer is 5 maps, and Discover Smaug is 2.
The strategy to defeat Smaug and win treasure is to lose the least might. Use T1 to cover your losses, and fill the rest of the attack with higher tiered troops to ensure victory. Using a single type of T1 is best, but the higher tier troops can be any tier or type to fill out your attack limit. For a basic 200+ hero and basic 20% Shield rune, send 35k T1 troops and 55k (or more) T5 or T4 troops. Since T1 lose you less might per attach/life star and they train fastest, they are the most efficient way to fight Smaug.
Using an rune of fury may lower the number of troops you need to send, but the rune of invulnerability (with basic shield rune) wil lower your troop loss. Higher life boosts like city guardian, permanent boost (Shield Wall) and hero gear further reduce losses per attack.