Today i was in arena and i was watching the bot. He played a totem from Shaman which gives adjacent minions +2 attack. There were 2 minions on the battleground and he played the totem on the left side instead of placing it between those minions. So only 1 minion had increased damage. Another one is the use of spells against a minion which says "Can't be targeted by spells or hero powers". He kept trying the spell "Hex" (The frog) on that card, if i didn't saw it, he wouldn't attack and keep trying the hex.
I hope i gave some usefull information right here.
