The 2017 Blue Book uses the term "playing tricks" but gives no definition. A google search came up with various different definitions.
How does the EBU define "playing tricks"?
‘Playing tricks’ is not a defined evaluation method in the Blue Book: it is used as a shorthand when describing hands with playing strength, not necessarily defence.
Partnerships should discuss what hands constitute ‘8 playing tricks’ to ensure they are on the same wavelength.
When explaining your bids to the opponents, you can use ‘8 playing tricks’ if the opponents understand that to mean ‘a distributional hand that hopes to be able to make eight tricks and does not show values outside the long suit (or suits)’. If the opponents will not understand ‘8 playing tricks’ as an explanation, then you should try and explain more fully.
While the EBU does not define playing tricks (correctly) because it does not use them, well, not in ruling the game, players do use them for deciding whether to open strong hands, pre-emptive hands and whether to overcall and if so at what level. As a result it might be a better question for one of the magazines.
The definition I learnt and adhere to is:
For the first three cards of a suit:
2.50: AKJ AQJ
2.00: KQJ AK
1.50 AQ KQT
1.00 A KQ QJT KJT
0.75: KJx QJx
I have probably missed out a few but you get the picture.
You then add one playing trick for every card over three in your longest suit.
If you have a second suit of more than three cards, you add one half of a playing trick for the fourth card, and one playing trick for each card over four.
Now we know why High Card Points/ Controls was chosen as the definition of 'strong'